We always park at Miami Fastpark. It's right across the street from the airport. A good part of the parking is under cover, although it's not guaranteed. The shuttles run continuously and they pick you up and drop you off at your car. Usually the shuttle to pick us up at the car arrives before we can get out of the car and get our bags out of the car. We have never waited more than 10 minutes, usually much less than that, at the airport, to be picked up. When you leave, you can get yourself a complementary bottle of water. I can't remember what the price is, but it's almost the same as long term parking at the airport and MUCH, MUCH better. Highly recommended!