I'm surprised no one's mentioned it yet...
Dragon's Dogma
The amount of control you have over your character is amazing, and the combat is truly stellar. Ever wanted to climb on a dragon while you're fighting it? How about a golem? A chimera? You can, and are basically expected to. It's got traditional RPG classes (fighter, strider/rogue, and mage) as well as advanced versions of them and hybrid classes.
The story may not be all that great, but the gameplay alone has kept me playing to the 120 hour mark. It's crazy fun.
If you get the chance, pick it up, and make sure you get Dragon's Dogma: Dark Arisen. It's the same game as the original, but with additional content.