We rented at the airport (MIA) and dropped it off at the HLE the next day and they have shuttle buses (three of them at the time) that just make cruise port runs dropping off and picking up. It was the same cost as airport only. On the way back we reversed it, picked up at the HLE and dropped off at FLL that evening, it was way less than paying a shuttle for two from the port to the airport.
The HLE was busy, but they were handled it well, I would use them again if needed. The wait for the shuttle on both ends was zero, there was one at the rental and at the cruise port waiting for people.