Okay, I'm back from Miami and reporting my experience. As I mentioned before, I just recently got matched to Avis First. With that came a free weekend. So I used Avis. Arriving at MIA, after the two day trek on the people mover to the train and then the train ride to the rental cars - whew! - I went down to where the cars were, spent 2 minutes at the window, chose whichever car I wanted from the group (not that many available, only 2 or 3, took the Rouge, and was off.
Returning the car I may have spent 15 seconds with the agent. As smooth as silk.
The bill, instead of 204 was 119 because of the free weekned. Keep in mind the taxes stay, just the car charges for two days disappears.
All in all a great experience. (And of course a great Purim in Miami Beach!)