Welcome from Florida! I can't comment on Galapagos, but I can comment about Florida. If you're wanting frequent diving, you should be looking at southeast FL in my opinion. I live in the Tampa area, and usually drive across the state to dive.
If you want shore diving, you want to be near Riviera Beach, FL. They've got Blue Heron Bridge, one of the best dives in the state in my opinion. It's shallow, free, and has easy access with nearby parking and a gently sloping beach. There is also plenty of deep boat diving just off the coast in that neck of the woods. From Jupiter Beach on the north end, to Lauderdale-By-The-Sea on the south end there is lots of good diving. LBTS used to have some decent shore diving but last I heard, a beach renourishment had ruined it.
Of course, you've got the keys. I believe there's diving on most of the keys, you just have to use a boat. I've dove Key Largo, Islamorada, Marathon. I preferred the diving in Marathon, but Largo seems to be the "dive capitol" as far as I can tell.
I'm trying to talk my wife into a move down to Miami so we will be in between the keys and the east coast sites I mentioned. There is some diving off of Miami but I haven't heard very many people talking about those dives. It's probably best to just go north or south if you live in Miami and have a vehicle.
There is diving on the Gulf of Mexico side where I live, but I prefer to drive across to the ocean myself.
In North/West Florida, you've got lots of freshwater springs and caves. I've certainly spent more than my fair share of time in the springs. The springs are breathtaking, but unless you get into cave diving you're likely to eventually tire of those.
Scubaboard holds some large semiannual dive events at
Ginnie Springs. One in the spring, one in the Fall.
The next one is at the end of this month. Usually somewhere around 100 people go. Might be a good chance to talk to lots of divers who know Florida pretty well.... if you're up for camping.
