L.P.
My 9 yr old loves the wii playground game, its handball, paper plane flying, easy introductory games that has her better at controlling the remote so she can play harder games with her sister. My 13 yr old thought it was a "baby" game at first, but she actually enjoys playing, too (just wouldn't let her friends know..haha!).
Good luck, and beware of wii addiction in mom's, too!! I love guitar hero!