A justified complaint about Wii Fit is the lack of workouts. Other pairings between Yoga and Strength exercises, there is no guidance about how to spend your workout. This allows for freedom and self moderation, but it also can lead to aimlessness.
I have put together four workouts. The first one focuses on the core, the second one focuses on the upper body, the third one focuses on the lower body, and the fourth one focuses on the three "challenge" exercises.
You can download my sheets for these workouts here: XLS PDF
Feel free to email/post comments/questions/suggestions!