I assume you have reservations, right? It sure isnt' a park you can often just show up at
One of the great things about the park, is you get the same benefits of those staying in the hotels. You get to participate in early morning hours (where one park a day opens an hour earlier for WDW guests) and late night hours, which means you get to stay in the park that is open late (well others may stay, but can't ride) 3 hours later than people not staying on site.So if a park closes at nine, and it's an extra hours day for that park, you get to stay til midnight!
Here it is from the horse's mouth (or Disney's Calendar). Keep in mind, if you don't have park hopper's, the park you plan on being in for extended hours, has to be the park you used your ticket on that day.
Here is the upcoming Extra Magic Hours schedule:
Morning Extra Magic Hours (park opens one hour earlier than the "normal" time)
Magic Kingdom® Park - December 2, 9, 16, 23, 25-31
Epcot® - December 5, 12, 19, 25
Disney-MGM Studios - December 6, 13, 20, 26, 30
Disney's Animal Kingdom® Theme Park - December 3, 10, 17, 24, 28, 31
Disney's Blizzard Beach® Water Park - December 25 - 31
Disney's Typhoon Lagoon® Water Park - December 1 - 24
Evening Extra Magic Hours (Park stays open for 3 hours later than the "normal" time.
Magic Kingdom® Park - December 7, 14, 21, 25, 30
Epcot® - December 1, 8, 15, 22, 27, 29
Disney-MGM Studios - December 4, 11, 18, 28, 31
Disney's Animal Kingdom® Theme Park - December 6, 13, 20, 26