L.N.
where about in florida? i just moved from south florida (west palm beach area) to MD. so i know that by march weather gets pretty warm though with cooler nights from time to time. so you definitely do not need jackets, need sunscreeen for her, hats, i think long sleeve shirts, but mostly short sleeves, and capris/shorts.
so basically, bring a few thin long sleeve shirts on top of stuff for warm warm weather.
don't know what you do for mosquitoes but they are alot down there and bite a whole lot. i never used an repellant for my girls, but when outside and in grassy areas i put long sleeve stuff so they don't get biten.
for airplane ride just get music stuff, lil toys and give her one at a time to keep her occupied.
good luck
vlora