Don't know about you but I always come back from the US with more luggage, sometimes way bigger, if not necessarily heavier (they sell very appealing stuffed animals in the parks [msnwink]). I'm really not a shopping person, but now I always bring an extra soft luggage for those $1 or $2 souvenir T-shirts, mugs, keychains, blah blah. And Florida is the place for bargains on well-known brands. All in all you cannot really escape it, and you want to bring back the usual souvenirs from the parks anyway.

I would go for the size I really need to begin with, as Katys Grandad says the cost isn't significant (less than £20 ?) and you might very well be upgraded to Premium which is even nicer. Renting a car in the US (from economy to full-size) I've always been upgraded, but maybe I'm just lucky [msnsmile].