I agree that Florida is generally warm-ish during winter or spring breaks - although that can vary greatly. Places like Discovery Cove are fun, but I will warn you - they can be very pricey. It seems most places in Orlando are not for the budget-conscious. Orlando is also crazy around the times of usual breaks from school, including the week of President's Day in Feb. and December break. Spring break is traditionally busy everywhere in Florida.
How about further south in Florida - the Everglades, Biscayne, the Keys? There are plenty of nature activities that are less expensive. Parts of the Everglades have well-groomed hiking trails and alligators in the wild (not to swim with, of course!).
The beach can be chilly, even in south Florida (except say, Key West), but you may get lucky. I've been to central Florida at the end of December and wished I'd had mittens. Then again, I've been on the beach in a bathing suit in December, too.
