The wind will largely depend on what cold fronts blow through during your time here. As a rule, that time in December can have some good wind, fingers crossed for your trip. How do you feel about waves?
There can be some nice wave conditions in Jupiter, fairly open beaches too. If you aren't used to waves it can be a demanding place to go. The same could be said about Ft. Pierce and to a lesser extent, Delray Beach. Miami has managed concessions in two primarily flat water venues like Matheson Hammock and Crandon Park which can have some waves on the outside at times. Access is a touchy issue in Miami given all the years of kiting and quantity of local residents, so you would probably be best hitting one of those concessions or even better taking a sea taxi to Stiltsville for some unusual kiting in a great venue.
You can kite both sides of Islamorada but only with a boat on the west or Florida Bay side. The wind is usually about 3 to 5 mph stronger in the Keys than the mainland due to the normal pressure gradient over the area.
I would bring a 3/2 full suit if you have one as the air temp can drop in strong cold fronts. Otherwise a shorty or even rashguard may serve in the more southerly points. In Tampa, you may want something a bit heavier than a 3/2 come to think of it depending on what blows through.
There are tons of riding options in Florida, checkout the top stickies for more ideas