When we were at WDW on NYE, they gave out party horns and hats. We were in MGM - had been in MK that morning - Mk was closed to anyone new entering by about noon. It was FULL! All the parks had the hats and horns and some live entertainment, but not anyone we recognized. Then all 3 parks had some magnificent fireworks at midnight. Be sure to make PS for at least one sit down meal - if you don't have a PS you won't get in. We had a PS, but saw many people who did not and they had to do counter service - which isn't bad, but it is nice to get to sit inside to eat during such a long time waiting for midnight. Oh, and by the way it was CROWDED!