I went for 2 and a half weeks late April/early May.
Obviously did the parks. Some were great, some good and some not so good. If you love Star Wars then Hollywood Studios is cool, especially the fireworks/hologram display at the end of the night.
Make full use of the waterparks as they are endless fun. Don't go on a weekend, only a weekday as it's far emptier.
If you are into a couple lazy days at the beach, go to Clearwater. It's about an hour and half drive but what a stunning beach. Well worth it especially if you want some chill time. You can surf there too.
Other things I'd recommend are swimming with Manatee's at Crystal River, it's quite surreal. You can also do an Airboat ride through the everglades and see plenty of Croc's but I wouldn't say you'd miss out if you didn't. Not really into Kennedy Space Centre but lot's of people seem to go there if you're into that kinda thing. Also a place called Forever Florida, a big cattle ranch where you can do horseback riding, Ziplines, a kinda Go Ape thing going on and swamp-buggy tours.
Make sure you do Discovery Cove. Amazing. Snorkling with all those fish and rays in the water is class. I did the Dolphin swim which was great too but again, it's not essential.
We also loved the little Mini Golf courses they have out there. Pretty good fun to be fair.
Go down to CityWalk and Disney Springs for a couple night's out, really good atmosphere down there with lot's of entertainment going on.
If you are fussed about info for the parks then the main thing I'd say is hit the busier one's in the week and leave the smaller one's to a weekend. Plan out your Fast Passes if you are doing any at any of the Disney Parks and if you are going to places like SeaWorld, Busch Gardens etc, it's a good investment getting those drink cups that are refillable because you can use them across several parks in the same category.
Some pretty quality places to go eat as well like Texas Roadhouse, Applebee's etc. I don't think there was one point where I managed to eat a starter, main course and a dessert in one sitting. Portions were just too big.