I don't really have any. Honorable mention goes to Mass Effect, though, which has the title of my most played game with a running total of 26 complete playthroughs. I just can't play it anymore without good reason, though. I literally know every single nook and cranny of the game. Runner up is Mass Effect 2, which is sitting at around 18 playthroughs. Both will probably get more when ME3 is released.
As far as hours, Fallout: New Vegas's ridiculous modding community is causing my hours to rack up on it at a worrying pace, and it's only just succeeded Fallout 3 in that regard.