I've lived in FL my whole life and while its definitely shorts-weather, I find that I feel much more comfortable in capris (granted I am heavy - size 16 - and I don't like my thighs rubbing together!).
I would not bring all jeans, especially because I see you are coming from Canada. October may be cool down here (it's when Mother Nature gets her Mood Swings on and changes from one day to the next!), but FL's version of 'cool' is not the same as Canada's version of 'cool', right?
I would say wear shorts or capris, but bring a pair or 2 of jeans, just in case. They won't take up that much space in the luggage (wear one pair on the plane down), and if you don't need them, then yay, but if you DO need them, double YAY!