Jill, when I first started out I used the basics, wii sports and wii sports resort but now I do fitness coach and gold's gym cardio dance. Cardio dance is the best one I've found, it's so much fun and on average you burn 10 calories a minute. How could you ask for more than that? What I like is that is has dancing, cardio boxing, and mini games that are a blast. The personal trainer option is what I use so everyday my rountines are new. Be prepared to sweat your butt off.
i've used wii fit, and wii fit plus, just dance (lots of fun.. but I'm a bit self conscious for it), sports, sports resort (I never use this much but my kids do), Sports active (this is a pretty good workout!). I think that's it so far. LOL