The Wii U is coming out next year, so I wouldn't waste my money on a Wii. If you want to buy something right now, I'd buy a PS3. There are enough games for kids (such as Ratchet and Clank) and it can double as a Blu-ray player so there's something for the adults, as well.
My family hasn't touched the Wii in months. The xbox/kinect is played constantly. I thought the novelty of the kinect would wear off quickly, but it hasn't at all. They LOVE that Kinectimals game. I think it's weird. Dance Central is a must!
Get one of these: Not only do games play better on them, but they also can do other things other than playing games