I've been trading games in at Amazon lately, they give more credit. Besides I don't buy as many games as before so I can't take advantage of GS stack system
I don't know about the rest of you, but Gamestop was pretty much the only trade-in system I used this year. Mainly because there's one less than 5 minutes away. Pure convenience.
I was told by the Gamestop closest to my house that I was banned from trading in during 2009 when I went to trade in for the 3rd time *EVER*. Going to go with Amazon.
I like Amazon. They give good amount of credit for most games, the trade in value is lock for few days, free shipping, and the Amazon credit is almost just as good as money.