I went to Florida three times in the past few years, each way a different route.
Firstly check out bargain flight websites - they may help (so not to advertise email me for a list)
Go to various airline sites and see what is on offer on your chosen dates
or the cheapest way i found was by a teletext bargain fly drive - cramped flight for 8 hours but you get a car for 3 weeks and your accomodation is usually got through the school
Enjoy