I can't speak much for Ft. Myers, and Orlando is obviously all about theme parks..but here's some ideas:
-You may have the time of your life without even leaving the airport. With the possible exception of JFK and LAX, MIA is the best place in America to spot exotic and awesome airliners from around the world.
-Miami, visit Cocoawalk in Coconut Grove...great shopping and dining. Check out the Miami Seaquariumhttp://www.miamiseaquarium.com/
on Key Biscayne. And the Bayside entertainment complex just north of downtown is great for people watching too.http://floridagoa.goacom.com/flalbum3.html
-Obviously you get a peek at the 'glamourous' people (or at least the ones who think they are) on South Beach. The Clubs and Bars are cool, but take a moment to take in the retro buildings, all built in the 1930s art deco
style (I'm told a design that was inspired by the French Liner Normandie
-In Lauderdale, check out the beach, Atlantic Blvd.....and spy some of the most incredible superyachts in the world. Also, FLL is becoming quite the spotter's gem too.
-The Keys....my favorite...
-Stop by the Dolphin Research Center on Grassy Keyhttp://www.dolphins.org/
...you can even inquire about their 'swim with dolphins' program.
-Not sure what your budget is, but in Marathon, about 2/3rds down the Keys to Key West, you can go for a genuine fighter jet ride aboard a Czech built L-39 Albatross trainer. Im told though that the fun starts at about $US800 an hour!
-Once you get to Key West....do the "Duval Crawl" down the main street and see some of the coolest pubs in the world. Visit the Green Parrothttp://www.greenparrot.com
at Southard and Whitehead streets...it's been a bar nonstop since 1890! Or visit http://www.sloppyjoes.com
where fabled author Ernest Hemmingway was a regular (his house is right down the street and open for tours).
And OF COURSE you're gonna need to wander down the street to Kelly's http://www.kellyskeywest.com/home.htm
...not only is this bar and restaurant owned by Hollywood star Kelly (Top Gun) McGillis, but it is located inside the building where a startup mail and passenger air transport company had its' offices in the early 20th Century...specializing in trips from Key West to Havana, that company called itself Pan American Airways! And you can see where it all began!
I also recommend an excursion out to the reef to snorkle...plus take in the sunset (an incredible sight here at the end of the world!) , either at Mallory Square (a tradition with street performers, magicians and more) or aboard one of the authentic schooners that sail out for the event.
My best advice on visiting Florida is to bring some spending cash...we are one of the world's great tourist traps and ripoffs do abound...and also do take care to stay out of 'less than desirable' areas....the easiest way to do that is to head for and stay on the big expressways and know exactly which exits you're looking for. Other than that, you'll have a GREAT TIME in America's Playground.