If you have siblings or someone to play the co-op mode with on the new super mario bros game I would suggest that. I have Mario Kart Wii and it got boring after a few hours. IMO it was the worst Mario kart on a console, but it does have some fans
Get New Super Mario Bros. That's what I'm getting for Christmas.
Mario Kart Wii isn't worth playing on Solo Mode, and it gets boring quick. Online mode is pretty chaotic and it can be REAL nasty; especially if you are playing with funky pros.
It's your choice. Rent Mario Kart Wii for you need to.