I like to play on Live, and I think a lot of games can raise their replayability points through online. Though, having to hear screaming immature little kids and so many trash talkers break the game a lot rather than make it.
*Coughhalo3cough*
RPG's are great though. Some games you may not want to play again for a year or so, but when you do replay it, you get to discover new things, try out different things, and catch up and comprehend things you missed the first time around. It almost re-locks you into it again, like the first time, which is really neat to me