Check out this site: http://miami.about.com/od/traveltourism/tp/attractions.htm I think the first 5 are a good idea. Personally, I would rent a car and head for the Keys! The Keys are the chain of islands off the southern tip of Florida - beautiful stuff!

One thing u MUST see before u come back is ur "ticket back home".

I'm from Florida but have only briefly visited Miami or driven through it, but... If the weather is nice definitely check out the beaches! I've never been to a beach in florida that I didn't like. Our beaches are usually a fine white sand. The Everglades our a very popular nature attraction. I've never been but I've heard great things from my friends who have. Now would be a very good time too since it's winter here. It shouldn't be uncomfortably hot, shouldn't rain, and there will probably be a lot less mosquitos. I second desertjedi's suggestion of visiting the keys if you have the time and resources. It's a simple lovely drive down that road connecting them and key west is a fun place to visit. It's got a nice historic district too. If you're into art maybe check out the galleries? I hear Miami has a thriving fine arts culture and the great Miami Art Basel is held there every year in December.