We have a Wii, that we bought Dc's for Xmas 2 years ago. There's not many days since that it hasn't been on.
They love it, esp Ds (6).
We do have a good selection of games now , but the main games ie Mario, wii sports etc are great fun and you usually get a good game with it when you buy it.
We also have a Ps2 , just upgraded to PS3, but they hardly play that, although it is Dp's so he plays on that alot.
In my opinion if you want a games console that's great for all ages then go for the Wii-the games are family friendly, and they do a lot of games for children.
The xbox and playstations , in my opinion cater for more serious gamers (adults) with their games, ie car racing, fighting/war games.