Real Racing 2 just updated for retina display, and that Sky Gamblers game that was shown in the announcement keynote is out as well and is getting really good reviews in the app store. It sounds like those are the perfect two choices for you!
I played Real Racing 2 maybe all the way through when I first got my iPad 2 some months ago, and I really enjoyed it even though I'm not a gamer (but if I have to choose, then it probably would be racing games and Street Fighter type games). I re-downloaded it yesterday to see the retina display update and it looked really great.