We'll need to know a lot more about your tastes before we can give you good answers. That said, if you liked Oblivion, try Fallout 3 (360). Guitar Hero: World Tour looks more and more awesome by the day, and you already have a guitar controller for your Wii, so it'll be fairly cheap. Gears of War II is the obvious answer if you enjoyed the original.
If you're going to get Force Unleashed (and judging from all the reviews, you may not want to...) then ask yourself if you prefer high graphics for the wow factor, or the extra levels and multiplayer mode. Whichever you pick will be the version you pick up.
Finally, if you're okay with going back to some games you missed, and you liked GTA IV you can try Crackdown (360) or Bully (preferably Wii because of the motion controls).
Again though, it'd be helpful if you told us what genres or games you're interested in...







