We are renting a Budget car at the airport the day before our cruise. I was under the impression we could pick the rental car up at the airport so we wouldn't need to worry about looking for baggage carts or a cab at the airport. We are staying at a hotel across the street from the Taylor Road Budget and dropping the car off in the morning before going to the cruise terminal. There is no extra charge to drop the car off there. We don't know yet whether we can get dropped off by Budget at the cruise terminal or if we need to take a cab. I don't think a cab is very expensive anyway.
Hope this helps a little,
One other thing - there is no additional charge for car rentals in Florida that are one-way. So you can pick-up at one location (say MIA or FLL) and drop off at another (say F07) without incurring any addition drop-off charge.