Where to get the most for a 360 console/games/accessories

[Invader Bugs]

Hey everyone, I'm looking to move on from my 360, but I'm looking for the best way to make the most from it. I have the 20gig premium console with the following games:

-Big Bumpin
-Gears of War
-Gears of War 2
-Guitar Hero 2
-Guitar Hero 3
-Guitar Hero World Tour
-Halo 3
-Marvel Ultimate Alliance
-Pocketbike Racer
-Rock Band
-Rock Band 2
-Sneak King

and a bunch of accessories like guitar controllers, drums, chatpad, some others. So, what would you recommend I do?