The Keys is where I have done a majority of my diving and you there is a ton of diversity, warm waters, great vis, and plenty of wrecks if you want to go beyond the shallow reefs. However, not mentioned is Venice Beach on the Gulf coast. It doesn't have the life of any of the other sites but is world famous for the fossilized shark teeth found on almost every dive. I made a one hour long dive last summer and surfaced with over 40 teeth. That was shore diving and if you take a charter out you can get some better locations and the rare Megalodon teeth are found farther out a bit more frequently as well.