Zumba on Wii should be good (I have it on xbox, but the wii version got better reviews). It has different workouts to choose from: 20-, 45- and 60-minute workouts for beginner, intermediate and advanced. Zumba fans will especially like it, just try to keep moving and you will sweat
I like that it gives the whole workout at once, not just one song at a time. Wii Sports could give you some arm workouts (boxing). Just Dance 2 and Wii Sports Resort may be worth looking at since they get you moving and will probably be fun.
Gamestop usually has decent (honest) reviews on games; Amazon has lots of reviews, but not sure on their accuracy. If you have a Gamestop, try to buy used and you have 7 days to trade if you don't like the game (or try to rent before you buy if you have a movie store). Hope you find something you like