At the Magic Kingdom, Mickey's Very Merry Christmas Party is the ultimate of all Disney's Christmastime events.
What's so special about MVMCP? There's two showings of a special parade holiday parade called, "Once Upon a Christmastime." A special holiday edition of "Wishes" fireworks, two special holiday stage shows, free cookies (gluten free offered) and hot cocoa, strolling carolers,"Santa Goofy" or who I call, "Goofy Claus." a souvenir family photo, and Snow on Main Street USA.
All of the popular rides are open with much smaller lines especially during the fireworks show or the parade.
MVMCP starts at 7pm and goes until 12am. Disney used to start letting people in at 4pm for the party, but that's no longer the case now.
There are still a few more dates that you an attend MVMCP: 12/14, 12/16, 12/17, 12/19. The best dates if you want to go when it's least crowded would be 12/14 and 12/16. Fridays are the most crowded because the locals are usually in attendance. Sundays are usually not too crowded, but the Orlando area schools are letting out on the 17th for the holidays so the 19th will probably be very crowded, especially since it's the last MVMCP for the year.
Mickey's Very Merry Christmas Party is a separate ticketed event. Prices ranging from are $53.95 or advanced purchase and $59.95 on the day of the event for adults (10+) and $47.95 and $53.95 for children (3-9).