I go to Florida most years (grew up there), and have just come back from a long weekend in NYC.
Presume you're going to Orlando? Shopping there is pretty good: Florida Mall and Millenia Mall are best, and then you can try the outlets too, but they can be hit and miss.
J Crew is $for £, so although upscale High St in thE US, it's MUCH better value in the UK, especially if they've got a promotion on. I've just come back with a Tippi jumper, some work trousers, and a basic LS tee. All full price but 25% off. Then in the sale I bought a sloppy jumper which was an extra 40% off.
I really like Victoria's Secret pants, and last week the assistants were handing out vouchers so you could get 7 pairs of their cotton pants for $26 (usually it's 5 pairs).
I always stock up on Secret deodorant gels: they don't leave white marks, and they have a range of lush fragrances, plus they work really well.
DKNY cozies are a bargain in the outlets, often 2 for $50.
I usually buy a pair or two of Lucky brand jeans as they suit my shape, but jeans are a good buy wherever you go.
Banana Republic is usually cheaper than here too.
iPads are a bit cheaper (IIRC about £50 saving on a mini).
I always buy loads of M&Ms: this time I've come home with almond, peanut butter and pretzel varieties.
Basically, either pack a spare suitcase or buy new out there:much cheaper.