Hi Cambridgeblue!
With 14 days, you have an opportunity to make a nice, counter-clockwise loop starting from Miami & heading along the north-east coastline to Fort Lauderdale, Key Biscayne, Miami Beach, Palm Beach & Coconut Grove.
From there, I'd suggest cutting west & enjoying the Orlando-Lake Buena Vista-Kissimmee area (lots of great theme parks there), then continuing west toward Tampa & coming out at Clearwater.
I'd check out St. Petersburg as you head south along the west coast, maybe Sarasota, but definitely stop a few days at the Everglades National Park. Leaving the Everglades, head further south to the Florida Keys, perhaps visiting the Dry Tortugas National Park (The nation's only at-sea national park). Allow one day's travel back to Miami to spend one last night there before catching your plane back home.
Here are links to 3 trips that would cover most of Florida for you. I'd save the 6-Day Family Trip In & Around Miami trip as your own, then add days & include the places noted in Most of Florida and 4 Keys in 4 days FL.
You don't mention if you're traveling as a single, couple, or a family, but you can easily change the activities to fit your personal needs & wants.
Have fun...with 14 days of sun ahead of you, you're bound to have an abundance of adventures...but don't forget to slip in a day or two of some serious beach lounging.
