Buying Wii or Wii U?

There is the original wii which is also a gamecube. Then there is a newer model which removed the backwards compatibility. There is also a 3rd model but it's pointless. If you can afford it you might as well go for the Wii U, since you said you had a working gamecube then you get to play everything.

They released Metroid Prime Trilogy for the wii. They updated the two gamecube games with wii controls etc, so you might be interested in that.