one of the things that i noticed has not yet really been talked about is the screen brightness.
if you set this to a lower setting, the game quality is still there, and actually having the screen brightness set lower can increase the battery life quite a bit. i think my max was roughly 6-7 hours on one battery charge with the lowest setting playing... Blade Dancer i think it was. (a nice little RPG game, however, quest objectives are slightly obscure, and hard to track).
as for reccomended games, what i like may be different from what you like, but, i do agree that crises core was fun, RPG games tend to last a lot longer if those are interesting to you, sport games have a good replay factor as you try to complete the seasons.
if you know anyone who has a few games, you can always to borrow them and see how things are going. If i remember correctly, you can return used games to Gamestop for 7 days i think? im not 100% certain if that has been changed though.