Go for Epic Mickey. Great gameplay and storywise... although it only requires a single player to get all the game experience... if you are a playing your Wii with your family most of the time, go for Donkey Kong Returns instead. It's more enjoyable that way.
DKC is a better game. It has tighter platforming and is fun in all the right ways. Epic Mickey's platforming is not only easy, but too easy. Not only that, the game mechanics (like combat) aren't really intuitive.
