If you are a PC gamer, avoid Gamestop. There is actually one in town here that doesn't sell PC games andy more, and those that do have a tiny section. Best Buy is a much better choice, they've got a whole isle of them (about the same amount of shelf space as any given console). Wal-Mart is also a decent choice. Target also has a reasonable number of games, but since they don't do a whole lot of shelf space for any system, including PC, their selection is a bit limited.
Online gets you a much larger selection, of course, but Best Buy is not bad at all if you want to buy from a store.