Have you ever been in Florida in the summer? It's a far cry from the Jersey shore; be ready for the humidity and relentless sunlight. Wear breathing material, use lots of sunscreen in the parks (especially on the kids), wear wide brim hats and consider using Body Glide or some other anti-chaffing product.
Get in shape! Even if you feel you're ready for the heat you'll have a better time if you are in your best physical condition and ready for the exercise.
I actually envy you, I'd love to go in the summer but I don't think DW would survive.
You must not live in the Northeast, I am from Philly and go to the Jersey Shore and we have heat index over 100 most days and it's blazing. I go to WDW every August and the nights in Disney or less humid. Yes it is very hot, but you are going in and out of air conditioning, it rains every day and it's not that bad if you plan accordingly. I do agree to walk every day ahead to prepare I barely use sunscreen in Florida and but it's not a bad idea. You will be fine drink lots of water, make use of early morning and evenings.
