@HappilyEverAfter80 - Wow!! that's nothing like our experience was at FLL and renting a car.
At MIA the rental car place is "off site" (not really, but almost). I remember that hike to where you caught the "monorail" to the car care center was pretty long, but the monorails ran pretty frequently.
and Yea, I don't really recommend driving, parking downtown Miami - its not a mess, but its not easy either. Thats one of the reasons we dropped our car off at Miami Airport and took Disney to the port (the more important reason is that we had first time cruiser friends with us and wanted them to get the "entire experience").
Our first time in Miami, we stayed at an airport area hotel and took their shuttle back to the airport to take
DCL transportation - because of the ease of doing it and it was our very first time in the Miami area and had no idea what to expect. I found that I kept watching the "Mickey and Gang go on a Cruise" video instead of looking around at the new sights