My personal heaven would involve shifter karts on a fast track with the Italian Alps as a backdrop. (I think I can be convinced on Alps in any other country too):
It won't matter if I'm just an average driver with the fastest kart in the field, just as long as I'm zipping by everyone. Oh, and I'd like an espresso and a tiramisu at the end of each session. You never gain weight in heaven, right? Throw in some gelato too then. And please don't wake me up...