I'm on the management team at my GameStop, and I've got two answers to this:
1. Doing midnight launches for games that I personally care about is actually really fun, and not agonizing at all. You get to socialize with all the fans, and enjoy the crowd to the fullest. Also, we really don't get out of work that much later than midnight.
2. If you're a smart employee like me, you work it out with your other managers to open on 11/10/11, so that you can punch out and get straight in line, than have the next two and a half days off to play the game