This is something I use to move my emacs frame around (I generally only have one open, albeit with 10-100 buffers open.) the `global-set-key` bindings at the bottom will be clearer documentation than any convoluted explanation. That said, it'll move / size the frame around the largest display, here's the shonky bit, the assumption is the largest…

mac-frame-adjust.el

;; mac-frame-adjust.el - emacs-mac-port frame-adjust tool. 
;; lots of preset frame size/positions in a convenient library.
;; Author: Jason Milkins
;; Requires: dash.el, s.el, cl-lib.el 
;; Emacs Mac-Port, frame adjuster - for my personal use only.
;; because it's not very good ;)
;; No warranty or support are offered.
;; However, it's licenced under the MIT Licence

(require 'cl-lib)
(require 's)
(require 'dash)

(defun mac-calculate-displays-list ()
  "List of displays on a Mac, each display is represented as (w h)
   e.g. (1280 1024)"
  (cl-mapl
   (lambda (str)
     (setq i (s-index-of "@" str))
     (when i
       (setq str (car (split-string str "@"))))
     (cl-mapl
      (lambda (str)
        (string-to-number str)) (split-string str "x")))
   (s-lines
    (s-replace
     " " ""
     (s-replace
      "Resolution: " ""
      (s-trim
       (s-chomp
        (shell-command-to-string
         "system_profiler  SPDisplaysDataType | grep -E 'Resolution' | tr -s ' '"))))))))

(defvar mac-displays-list (mac-calculate-displays-list)
  "memo of mac-calculate-displays-list - List of displays on a
   Mac, each display is represented as (w h) e.g. (1280 1024)")

(defun mac-largest-display ()
  "return the dimensions of the largest Mac display/screen"
  (let*
      ((d-list (cl-mapl
                (lambda (d)
                  (--reduce (+ acc it) d))
                (mac-displays-list)))
       (d (reduce 'max d-list))
       (i (position d d-list )))
    (nth i (mac-displays-list))))

(defun mac-largest-display-pixel-width ()
  "pixel width of largest disply"
  (car (mac-largest-display)))

(defun mac-largest-display-pixel-height ()
  "pixel height of largest disply"
  (nth 1 (mac-largest-display)))

(defun mac-set-frame-position-top-right-hand-side ()
  "Position the current frame to the top/right of the Display"
  (interactive)
  (if window-system
      (progn
        (set-frame-position (selected-frame) (- (mac-largest-display-pixel-width) (frame-pixel-width)) 0))))

(defun mac-set-frame-position-top-center ()
  "Position the current frame to the top/center of the Display"
  (interactive)
  (if window-system
      (progn
        (set-frame-position (selected-frame) (- (/ (mac-largest-display-pixel-width) 2) (/ (frame-pixel-width) 2)) 1))))

(defun mac-set-frame-position-top-left-hand-side ()
  "Position the current frame to the top/left of the Display"
  (interactive)
  (if window-system
      (progn
        (set-frame-position (selected-frame) 0 0))))

(defun mac-set-frame-height-to-display-height ()
  "Size the current frame height to match display height -
nb:approximately, Emacs sets frame height by char rows."
  (interactive)
  (if window-system
      (progn
        (set-frame-height (selected-frame) (/ (- (mac-largest-display-pixel-height) 90) (frame-char-height))))))

(defun mac-set-frame-height-to-85-percent-display-height ()
  "Size the current frame height to 85% of display height -
nb:approximately, Emacs sets frame height by char rows."
  (interactive)
  (if window-system
      (progn
        (set-frame-height (selected-frame) (floor (* (/ (mac-largest-display-pixel-height) (frame-char-height)) 0.85))))))

(defun mac-set-frame-width-to-two-thirds-display-width ()
  "Size the current frame to two thirds the display width. -
nb:approximately, Emacs sets frame width by char columns."
  (interactive)
  (if window-system
      (progn
        (set-frame-width (selected-frame) (/ (round (* (mac-largest-display-pixel-width) 0.66)) (frame-char-width))))))

(defun mac-set-frame-width-to-three-quarters-display-width ()
  "Size the current frame to three quarters the display width. -
nb:approximately, Emacs sets frame width by char columns."
  (interactive)
  (if window-system
      (progn
        (set-frame-width (selected-frame) (/ (round (* (mac-largest-display-pixel-width) 0.75)) (frame-char-width))))))

(defun mac-set-frame-width-to-half-display-width ()
  "Size the current frame to half the display width. -
nb:approximately, Emacs sets frame width by char columns."
  (interactive)
  (if window-system
      (progn
        (set-frame-width (selected-frame) (/ (/ (mac-largest-display-pixel-width) 2) (frame-char-width))))))

(defun mac-set-frame-width-to-quarter-display-width ()
  "Size the current frame to quarter the display width. -
nb:approximately, Emacs sets frame width by char columns."
  (interactive)
  (if window-system
      (progn
        (set-frame-width (selected-frame) (/ (/ (mac-largest-display-pixel-width) 4) (frame-char-width))))))

(defun mac-set-frame-width-to-third-display-width ()
  "Size the current frame to quarter the display width. -
nb:approximately, Emacs sets frame width by char columns."
  (interactive)
  (if window-system
      (progn
        (set-frame-width (selected-frame) (/ (/ (mac-largest-display-pixel-width) 3) (frame-char-width))))))

(defun mac-set-frame-width-to-display-width ()
  "Size the current frame to half the display width. -
nb:approximately, Emacs sets frame width by char columns."
  (interactive)
  (if window-system
      (progn
        (set-frame-width (selected-frame) (/ (- (mac-largest-display-pixel-width) 30) (frame-char-width))))))

(defun mac-set-frame-maximize ()
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-position-top-left-hand-side)
        (mac-set-frame-width-to-display-width)
        (mac-set-frame-height-to-display-height))))

(defun mac-toggle-kiosk-mode ()
  "Toggle full screen"
  (interactive)
  (when window-system
    (set-frame-parameter
     nil 'fullscreen
     (when (not (frame-parameter nil 'fullscreen)) 'fullboth))))

(defun mac-set-frame-left-w25-h100-percent ()
  "A convenient preset frame size & position - 25% width, 100%
height, top/left position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-display-height)
        (mac-set-frame-width-to-quarter-display-width)
        (mac-set-frame-position-top-left-hand-side))))

(defun mac-set-frame-right-w25-h100-percent ()
  "A convenient preset frame size & position - 25% width, 100%
height, top/right position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-display-height)
        (mac-set-frame-width-to-quarter-display-width)
        (mac-set-frame-position-top-right-hand-side))))

(defun mac-set-frame-right-w30-h100-percent ()
  "A convenient preset frame size & position - 30% width, 100%
height, top/right position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-display-height)
        (mac-set-frame-width-to-third-display-width)
        (mac-set-frame-position-top-right-hand-side))))

(defun mac-set-frame-left-w50-h100-percent ()
  "A convenient preset frame size & position - 50% width, 100%
height, top/left position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-display-height)
        (mac-set-frame-width-to-half-display-width)
        (mac-set-frame-position-top-left-hand-side))))

(defun mac-set-frame-left-w66-h100-percent ()
  "A convenient preset frame size & position - 66% width, 100%
height, top/left position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-display-height)
        (mac-set-frame-width-to-two-thirds-display-width)
        (mac-set-frame-position-top-left-hand-side))))

(defun mac-set-frame-left-w75-h100-percent ()
  "A convenient preset frame size & position - 75% width, 100%
height, top/left position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-display-height)
        (mac-set-frame-width-to-three-quarters-display-width)
        (mac-set-frame-position-top-left-hand-side))))

(defun mac-set-frame-left-w75-h85-percent ()
  "A convenient preset frame size & position - 75% width, 85%
height, top/left position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-85-percent-display-height)
        (mac-set-frame-width-to-three-quarters-display-width)
        (mac-set-frame-position-top-left-hand-side))))

(defun mac-set-frame-right-w50-h100-percent ()
  "A convenient preset frame size & position - 50% width, 100%
height, top/right position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-display-height)
        (mac-set-frame-width-to-half-display-width)
        (mac-set-frame-position-top-right-hand-side))))

(defun mac-set-frame-right-w66-h100-percent ()
  "A convenient preset frame size & position - 66% width, 100%
height, top/right position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-display-height)
        (mac-set-frame-width-to-two-thirds-display-width)
        (mac-set-frame-position-top-right-hand-side))))

(defun mac-set-frame-right-w75-h100-percent ()
  "A convenient preset frame size & position - 75% width, 100%
height, top/right position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-display-height)
        (mac-set-frame-width-to-three-quarters-display-width)
        (mac-set-frame-position-top-right-hand-side))))

(defun mac-set-frame-right-w75-h85-percent ()
  "A convenient preset frame size & position - 75% width, 85%
height, top/right position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-85-percent-display-height)
        (mac-set-frame-width-to-three-quarters-display-width)
        (mac-set-frame-position-top-right-hand-side))))

(defun mac-set-frame-top-w100-h50-percent ()
  "A convenient preset frame size & position - 100% width, 50%
height, top of screen."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-percent-of-display-height 50)
        (mac-set-frame-width-to-display-width)
        (mac-set-frame-position-top-left-hand-side))))

(defun mac-set-frame-bottom-w100-h50-percent ()
  "A convenient preset frame size & position - 100% width, 50%
height, bottom of screen."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-percent-of-display-height 47)
        (mac-set-frame-width-to-display-width)
        (set-frame-position (selected-frame) 0
                            (floor (* (mac-largest-display-pixel-height) 0.51))))))

(defun mac-set-frame-height-percent-of-display-height ( percent )
  "Size the current frame height to a given percentage of the
current display height - nb:approximately, Emacs sets frame
height by char rows, so we calculate from the current frame
character height"
  (interactive "nPercent: ")
  (if window-system
      (progn
        (set-frame-height (selected-frame) (floor (* (/ (mac-largest-display-pixel-height) (frame-char-height)) (/ percent 100.0)))))))

(defun mac-set-frame-to-footer ()
  "Set the frame to a convenient position at the bottom of the
screen, changing the height and width too. Width will be set to
100%. Height set to 37%"
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-percent-of-display-height 37)
        (mac-set-frame-width-to-display-width)
        (set-frame-position (selected-frame) 0
                            (floor (* (mac-largest-display-pixel-height) 0.61))))))

(defun mac-set-frame-center-w50-h100-percent ()
  "A convenient preset frame size & position - 50% width, 100%
height, top/center position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-display-height)
        (mac-set-frame-width-to-half-display-width)
        (mac-set-frame-position-top-center))))

(defun mac-set-frame-center-w75-h100-percent ()
  "A convenient preset frame size & position - 50% width, 100%
height, top/center position."
  (interactive)
  (if window-system
      (progn
        (mac-set-frame-height-to-display-height)
        (mac-set-frame-width-to-three-quarters-display-width)
        (mac-set-frame-position-top-center))))

;; Some defaults for quick access. (24 == C-x)

(global-set-key (kbd "C-x M-<left>") 'mac-set-frame-left-w66-h100-percent)
(global-set-key (kbd "C-x M-<right>") 'mac-set-frame-right-w66-h100-percent)
(global-set-key (kbd "C-x M-<down>") 'mac-set-frame-to-footer)
(global-set-key (kbd "C-x M-<up>") 'mac-toggle-kiosk-mode)
(global-set-key (kbd "C-x C-M-<left>") 'mac-set-frame-left-w50-h100-percent)
(global-set-key (kbd "C-x C-M-<right>") 'mac-set-frame-right-w50-h100-percent)
(global-set-key (kbd "C-x C-M-<up>") 'mac-set-frame-top-w100-h50-percent)
(global-set-key (kbd "C-x C-M-<down>") 'mac-set-frame-bottom-w100-h50-percent)

(global-set-key (kbd "C-x M-s-<right>") 'mac-set-frame-right-w30-h100-percent)
(global-set-key (kbd "C-x M-s-<left>") 'mac-set-frame-right-w30-h100-percent)
(global-set-key (kbd "C-x M-s-<up>") 'mac-set-frame-center-w50-h100-percent)
(global-set-key (kbd "C-x M-s-<down>") 'mac-set-frame-center-w75-h100-percent)

(provide 'mac-frame-adjust)