I'm not sure where you are located, but if you drive down US1, there are still some neat places left from the big tourist boom. Lots of vestiges of a more optimistic time floating around right off the road. Many are disappearing fast, being replaced by McMansions, but there is plenty to work with.
The big list above is great, I've shot at most of those places and found a lot of material to work with. The Alligator farms are good during breeding season (just ending) if you shoot any color film. I've got some good shots of nesting egrets from just a few feet away - they nest just off the boardwalks so you get to be right there without scaring them off.
Let's see, there is DeLeon Springs sugar mill, a couple of other sugar mill ruins in East Central Florida (Yulee and Bullow Plantation), um, St. Augustine is pretty rich in subject matter, and so are some of the old forts along the East Coast. I'm not overly familiar with the West coast, but I'm certain there is good stuff there. I found the State Parks system to be quite useful - it has won numerous National awards for excellence, and for good reason.
I'm sure that as soon as I post I'll come up with more, but for now that about covers it.
Oh, wait! For flowers there are about 4 or 5 gardens (Leu Garden, Washington Oaks, Marie Selby, and a few others) scattered over the state. Just search for 'Florida Gardens' and you should be able to get directions.
Ok, that's it for now. Be sure to post anything interesting you find for the rest of us!
- Randy