I usually have a huge numbers of files, related to my projects. I would like to use attach to associate the files with the proper entry, but searching them later in my Dropbox is a pain because of the way Org saves the attachments. It makes more sense for me to make attachments follow the org tree structure in the project by default (unless I change the attach folder to something else).
This can be done if we make attachment by creating a symbolic link to the attach folder in the place, according to the headline path. This way allows to keep all the file attached to the project accessible with relative paths.