I live in Valrico, sort of a middle to upper middle class suburb of Tampa. Parts of St. Pete are very wealthy, however, I would tend to think that you may have the highest possibility of sucess in the Sarasota/Bradenton area. There is a lot of money down there. I think that the Tampa are and it's suburbs have a lot to offer you as well. I think no matter where you go, you are going to have a lot of competition. The green industry in Florida is pretty saturated, however, it always seems like there is room for more. A lot of the businesses you see out and about in a daily basis probably wont be around in a year or two, and a lot do shoddy work. There are wealthy areas in all of the areas you listed, as well as pretty poor areas.
One of the good things about South Florida, though, is the grass grows year round (for the most part). We have no state tax down here either, and the cost of living is probably lower than in NY.