As for RPGs:
Dragon Age Series (Origins, Awakening and DA2) already exists for Mac. Dragon Age 2 is Mac and PC on same DVD and should be possible to get on every store that sells games in the world.
Two Worlds 2 is for mac now
Assassins Creed 2 is also for mac now
Elder Scrolls Oblivion, does not exist on Mac, but Crossover rates it Gold (which means it runs very well)
Older RPGs like
Gothic 1 and 2 runs well in Crossover,
Gothic 3 has issues, but I've made my own Cider wrapper and have played the game to lvl 45 with no issues at all.
The Witcher runs oki on crossover (some people has graphics issues tho), but there is a bug where you can't see your health bar..
Risen is pretty much a no go too, tried about everything there is and unless you can play with no mouse it's no good in osx.
Fallout 3 and New Vegas will also work with some effort, if you don't wanna spend time tweaking those aren't for you
Drakensang River of time was rated gold at crossover, but because you have to apply a no-cd crack they removed it. With a No-CD crack it runs very well.
There is a bunch of wrappers at the RPG section of
portingteam
but be sure you get the game from a source with no DRM (gog and most retails, do not buy on steam

) or be prepared to have to use a no-cd crack on your own legally bought game.