Bored for ideas :S
Have you tried Dark Sector, the multiplayer achievements are pretty hard to achieve.
You should try posting any game related question in the general game discussion thread. As you will get a greater response.
Mainly RPG's are mostly re-playable, if you try every option / class / character.
Why don't you try Mass Effect 2, or Fable 2? They're all good games to play and re-play.