Next generation systems will be coming out soon, I'm under the impression Microsoft and Nintendo will be pushing something out next year. The game development on the 360 and PS3 is more mature content, suited for hardcore gamers, while the game development on the Wii is suited for children and casual gamers. However you can get the 360 and kinect and get best of both worlds. Sony and Nintendo also have portable, handheld gaming systems which might be something to look into. So IMO I would get the 360 slim and kinect bundle. Kinect is controller free motion sensing gaming. The kids would love it and they can play the standard xbox 360 system as well.
To be honest I really like tablet gaming either on android or iOS. It's very addicting and there is a ton of developer support on either platform. Not to mention a lot of cheap and free games.
