Greetings to all your Florida Experts

My fiancee and I fly into Miami during the evening of April 20th and plan to stay in an airport hotel before driving up to Orlando the following day.
We have heard various reports about tourists being targeted in Miami and it has been suggested that we do not pick up our hire car until the following morning.
Do you think this is the most sensible option?
Do you have any suggestions on hotels that run a shuttle service at Miami Airport?

Also, we plan to end our trip with a jaunt down to Key West, leaving Orlando on Wed 30th and eventually arriving at Miami for our evening flight back to the UK on Saturday 3rd May.
Does anyone have a suggested itinerary of things not to miss in the Everglades and the Keys. We did the Gulf Coast (Tampa & St Peterburg) last year so we want to make the most of our trip without spending all our time in the car!
Any attraction or hotel recommendations would be greatfully received as well.....

Many thanks in advance
Leslie