I've been converting my garage to a game room for the last year or so. I have three separate circuits wired for various sections. Plus on the cieling is an excellent suggestion. I ran a couple extra in the ceiling for cieling mounted TV's (still need to hang them). Remember you might also have NEON, Rope light, signs, etc so the more power you can supply the better. GFI plugs are not necessary, but are nice to have.
My garage / game room is a 3 car. I sheet rocked all the walls and built a couple of enclosures for Laundry / Furnace and now building a hidden shelving unit. After sheetrocking I looked at the place and figured I had two options for painting. Option one was to apply two coats of primer to seal it and one to two coats of conventional paint for appearance. Option two was to skip priming and move directly to paint. Normally this wouldn't be recommended, but I found a "texture paint" at Home Depot that you basical slop it on and spread it arround. It sealed rock solid within 24hrs and is easily cleanable by water and sponge, etc.
You can see a picture of what the texture paint job looks like
here It should be a hi res enough picture to make out the texture. The fridge and freezer that are seen in the pic are now hidden in another enclosure with oak doors and the remaining section of that same wall will be a storage unit when I am done.
The game room is currently a mess... Hopefully this weekend I will get it organized enough to snap some pictures (after the new cab arrives).
-Goz