Mario Kart Wii
Like practically every other Nintendo Wii owner, we're playing Mario Kart Wii. We loved Mario Kart on the N64 and I think this version will hold the same lasting enjoyment (though hopefully we can complete it a little quicker).
And controlling the cart with the wheel? So cool! I think the automatic drifting by turning hard makes the game a bit more fun, though certainly has less control advantage. We've only played a handful of tracks, but they're all fun. Highly recommended.