While not necessarily as training-efficient as your next Pilates Session, Wii Fit is fun for the whole family.

User Rating: 8 | Wii Fit WII
When I received Wii Fit, I was essentially in it for the Balance Board, and ended up with the most family-friendly crowd game yet. While not a multiplayer hit, it gets the entire room going, laughing and holding their breath, as they watch the player (or players) rocking on the balance board. The main draw, obviously, is the innovative Wii Balance Board, which is compatible with not only Wii Fit, but a good 5-6 other games. The Board is absolutely spot-on, and while it may take some time to get used to, you will undoubtedly get the hang of it after maybe 10 Fit points at most. (Fit points are gained by doing the individual games & exercises, usually receiving 1-2 points per exercise). It's sensitivity is impeccable, detecting even the slightest movement or shift in weight.
The game itself is split into four sections: Yoga, Aerobics, Strength Training, and Balance Games. My personal favorites are the Strength & Balance, simply because those are actually games, and crack me up every time. The Yoga & Aerobics, while not as comically pleasing, are very calming & your personal trainer (male or female, by choice) is great. If you happen to do a certain exercise incorrectly, or you just can't get the hang of it, they will guide you through & make sure you can understand everything.
All in all, Wii Fit is a very solid, and, at times, hilarious game (like during the soccer header game, your Mii has to dodge a hit in the face by a cleat or *random* panda head). The Balance Board is the easily the most innovative peripheral for the Wii, and will satisfy your every craving, from Ski Jumping to mastering the Warrior pose. (And for the record, my Wii Fit age is a resounding 21 years old.)