Remember that time you walked into a big chain store with a shopping bag full of games, thinking you were going to cash out big time, only to leave with a gift card housing barely enough credit to grab even one new game? Of course you do; we've all been there.
I'd rather go Wal-Mart or Best Buy. I know that regardless of which one I choose and if they have to give me in-store credit, I'll be able to put it to use without worry. I mean I could probably spend hundreds of dollars in Best Buy without a problem. I also know they're pretty good on trade-ins. I took a few 360 games back and seemed to get more from them than from Gamestop.