If you really, really want to go at Christmas, be prepared! We were there last Christmas (arrived 27th and departed the 2nd) and I have never seen so many people all in one spot at once. Thankfully, our past experience at WDW helped us get around the packs, fast passing, etc. but I felt sorry for any one who picked that time of year to go as their first time. If you can, I would highly recommend going the week or two before Christmas (have been at this time and it's absolutely wonderful) - you will enjoy the beautiful decorations and ambiance without the crowds. The upside - it's not hot and humid. You'd have to make sure the hotel you stay at has a heated pool as it can be jacket weather. The parks were open pretty late and had two sets of fireworks each night, one around 8:30 and one later (11:00 ish), if I remember correctly. New years eve was fun - kind of like being at one giant party. But again, can't stress enough about how helpful it is to know your way around and use effective time management. Would we go again at that time? Probably not, but on the other hand, don't regret the trip at all.