Hi and welcome to the DIS,
just really to agree with Jools. The weather, generally, is pretty mild in Florida although you can get the occassional cold snap. I would suggest taking one fleece/sweatshirt each and maybe a cardigan for women and children. If you're unlucky and it lasts more than a couple of days there are plenty of places you can pick up some cheap extra warm clothing. I tend to do a lot of my shopping for these sort of things in Florida (because it's very cheap) so I usually don't take much warm stuff with me.