I did that trip in May.
1. Get some US sports in if you can I was looking for a basket ball match but it was already in the playoffs and the tickets were difficult to get and pricey, still I drove over to Tampa Bay and saw the Wrays.
http:// tampabay.rays.mlb.com/index.jsp?c_id=tb
1. Not sure if it is the season at the moment with NFL on now but was not too expensive 39 USD plus parking and worth it.
2. Went down Highway 1 and stayed at a cheap hotel in Key Largo - next to the road was some industrial stuff but just behind was the marinas and stuff - definitely do the water sports thing.
3. Car hire - we landed at 03:00 hrs in Orlando (Volcano) International and our Car Rental Company was the only one open! We got a Hyundai Sonata and the quality of the car and effectiveness of the air con was top notch.
4. Sea World and the Alligator / Crocodile farm was cracking, well worth a visit. Alligator wrestler, where are you going to see that in Ukania?
EDIT/
I recommend the sunpass too, much easier. You will need a US enabled Sat Nav - or get one on the rental (Expensive Option).