Maureen, I answered this question in the general cruise chat area, but in case you miss it: The Days Inn North (on NW 36th St.) at the Mami Airport offers a free shuttle service from the airport to the hotel and from the hotel to the port. Prices are reasonableand they have a very nice pool.
I have been to Miami a few times. I suggest getting a cab instead of a shuttle. It is a quick way to get out of the airport. It is about $20 to go to South Beach and stay at a hotel along the ocean. You can find reasonable priced hotels and a great view of the ocean and beach. A cab to the port is about $20 too.