Access to the wonderful Acetate tileset was lost when ESRI shut down GeoIQ. There are a few ways one might deal with this
- Host your own version of Acetate using the stylesheets, data, and instructions in the Acetate repo on GitHub (link)
- Try to recreate it using something like Mapbox Studio.
- Run another tileset through a tile filter like TileLayer.Grayscale.js
This map demonstrates the third option. In this map, MapQuest's tiles are run through TileLayer.Grayscale.js to create a grayscale version of their tiles. A variety of tilesets can be found on Leaflet-providers preview.