That is allot of territory. Destin is nice, actually really nice but its light years away from everything else you mentioned. Like 10 hours away.
Anyway I like your plan. Leave it a bit loose. The keys are nice but its 5, maybe 6 hours drive down the overseas highway. If you find yourself on the gulf coast you can hop a fairy from Fort Myers (that has a nice cable) or Marco Island (that has Baitkillers Nautique) that will get you there in 3 hours for pretty reasonable.
Cape Canaveral is really cool and a full day and well worth it, kids loved it.
I'm done with Disney
Busch Gardens is under rated.
Revolution Cable is really good.
There is a system 2 in Grassy Key that is fun if you drive to the keys. FYI.
Hobos in Islamarada is a great place to stop for grub.
There is a Top Golf in Tampa now.
The Tampa Aquarium is really good.
Schooner Warf bar in Key west for 10:00 AM Rolling rocks.
Pepes' in in Key West for breakfast or dinner, recommend the steak smothered in porkchops.
Card Sound Road can save you 1/2 an hour but will cost you a buck.
Carowinds in Charlotte NC. has great coasters and entrance is like $40. The only theme park I have ever been to that I didn't leave feeling A$$ raped and cant wait to go back. A bit grubby but super fun.
Everglades tours have fallen off a bit. Speedys is pretty good. Make sure you do a small 6 person boat, not a big one. (air boats) Go to check out Ted Smallwoods store (google it) and poke around the area a bit. Lots of little, easily overlooked Americana to be found. The Rod and Gun Club in Everglades City has gone down hill as of late. Shame. It used to be "dressed for lunch on the veranda".. not so much since the buses started showing up.
Have fun in my backyard and holler if you need a pull.