We have met many folks that have gone to Florida without reservations.
Some were okay with the results and some were not. I cannot tell you how many people we've seen driving out of park after turning around because park was filled (state parks). Usually the next time, they get it together to make reservations even if it is a few days here and a few days there to see what they like.
Visit some of the coast areas if you can get a reservation...west and east.
Donna