L.M.
I went to St. Augustine last October for work. Loved the town but didn't get to explore too much. Definately want to go back.
There is also Sea World...we did that when we went in April 2009 but we also went to the Disney Parks too. When I went many years ago, we did Lion Country Safari. When I was 16, we went to Busch Gardens and Naples...which was nice too.
Good luck.