We got chased off the Keys a few years ago by a hurricane and since we still had some time decided to fish for peacock bass in some of the canals in/around the city; had a blast. Here's a guide to some of the spots:
We used mostly Clousers and bunny strip flies; couldn't get them on topwater but that may have just been the time of year (about when you'll be there). Also note on those links that they advise against leaving valuables in your car - this is an urban fishery and some parts of Miami can be a bit sketchy; we never had any issues but we may just have been lucky.
I would try saltwater - go for whatever is biting at that time; bonefish, snook, permit, tarpon, redfish, and bring ~$500 for a guide with a boat (and other equipment -correct rod/line, etc., if you don't have it). A partner would help defray expenses.
HIGHLY recommend you thoroughly check out the guide - if you elect to hire one. The last time I went (Islamarada) I wanted to specifically fish for Tarpon WITH A FLY. The guide I ended up with (my fault) admitted he did both - but it was obvious he preferred casting crabs and minnows and did not really know his flies. He told me the tarpon were not in town and we chased some bonefish instead - no hook - ups, although we saw a few schools. I also happened to see an armada of tarpon swim by . . . 30 feet from the boat!!! It's not my style to bad mouth a guy trying to make a living - but this was a very big learning lesson for me. I'll be exact about what I want in the future and will not settle when I'm shelling out 5+. I was not happy with that outing.
I think that a member here guides North of Miami a bit. His name is Onlyonthefly. He posts in the saltwater forum. You could also fish from shore in several areas around inlets to the inter-coastal waterway. Try early in the AM before all the sun bathers head out.