I've got a tip for a good location. The finish line of the Columbus Day Regatta. The Regatta is the weekend of October 6th and 7th, and it is the largest boat party in Miami. Bring a case of beer and a camera.
I lived in Miami the first 25 years of my life and I never did see the actual regatta, just the party afterwards. The times I attended the party has been on the bay side of Elliot key in Biscane bay.
If you will not be in Miami on that weekend what I would suggest would depend on how many people you have going with you. If it just you and your girlfiend, you can jump on a big charter that takes 30-40 other people out. The boat stops and you just thow in your line.
If there are a couple more of you, you can split the cost of a charter that will take you out blue water fishing for Marlin, Sail, Tuna, or whatever. That is a lot of fun, but a lot of money.
You can always get a charter and try for some bone fish on the flats.
Sorry, but I can't recommend a good boat. I've always either gone out on my own boat or a friend's.
It's been a long time since I've been out, over four years, and I miss every minute of it. There were times in college, during summer, when I would go out every day for two weeks straight. Talk about eating fish for months...
Good Luck and I want to see the picture of the sord fish.