The accommodation at the state parks tends to be VERY basic. We looked at the cabins at the Myakka River state park and I wouldn't have stayed there in a million years, and certainly not with small children.
I am pretty sure that there will be others who say it's not that bad but i am talking as somebody who doesn't 'do' camping or sleeping rough so, if you like that sort of thing, you will probably be fine.
You just need to be aware that the cabins etc. are basic. I read a trip report on another site, written by somebody who stayed at Bahia Honda and they had to make their own beds up when they arrived and everything. There was no television, no mod cons. I couldn't be doing with having to make up my own bed after a long journey, no thank you very much.