I haven't been to Miami in a long time, but I remember it as being a gorgeous place with a wealth of things to do. Whenever I plan a trip I always call the Chamber of Commerce in that area. They seem to be the go-to spot for dated events. But here's some links on the top 10 to 100 best things to do in Miami:
http://miami.about.com/od/traveltourism/tp/attractions.htm
http://www.miami-info.com/
http://www.miamibeach411.com/news/101-fun-attractions-in-miami.htm
I'll bet you'll have a great time!
-nab