Norm we have used unitedairportparking .com to find parking in Miami. The lot you get on there is near the airport, is fully enclosed and they have a shuttle service to the port and back. For a 7 night cruise it was about $76, it is valet only parking, but they do have some undercover most open air. I just found out about the Rodeway Inn on 14th near Jackson Memorial Hospital and they have parking for $5 a day and shuttle service to and from the port included.
For last weeks cruise we parked at the Wyndham near the airport and while the price for parking was good there was $8 in taxi rides so it actuuall cost mor that we have been paying.
If you email me I will give you more info.
Star Princess 2005, Sun Princess 2005
Caribbean Princess 2006, MSC Lirica 2006 , NCL Pearl 2007, Majesty of the Seas 2008, Carnival Destiny 2008, MSC Lirica 2009, Carnival Valor 2009,Carnival Legend 2010, Carnival Liberty 2010,Carnival Fantsay 2011,Carnival Valor Feb 2012, MSC Poesia Dec 2012, MSC Poesia April 2013, Carnival Legend Nov 2013, MSC DIVINA Jan 2014