There are lots of direct flghts to Orlando with multiple airlines from those three cities. Browse around for the best fares and schedules. Check these airlines:From New York JFK:JetBlueAmericanDeltaFrom Philly:US AirwaysAirTranFrom Newark:Continental
Steer clear of JFK during the holidays. It s a very nice airport, but it will be congested with all the people coming home after Christmas. Philly will probably be your best bet, relatively quick in and out. Allow yourself at least 1.5 hours between connecting flights. That way you can get out, stretch your legs, and maybe grab a bite to eat. Good luck.