Many of the restaurants especially in the resorts start serving early and go through the evening. I have seen this at Whispering Canyon and Yacht. St. All of the disney restaurants offer a traditional xmas dinner as their special for the day.
Suggestions:
Resorts-Cal Grill, Concourse ST, Whispering Canyon, Artist Point, GF Cafe, Konas, Yachts St, Boma, Trails End.
Parks- LTT, Cindy's, Prime Time, Mama Melrose, Brown Derby, Any of the WS restaurants.
Keep in mind with the park restaurant you choose what time you will be entering the Park. A good example is MK which always filles to capacity by 11am on xmas day. So trying to get in later in the day may be difficult.
Remember to make your PS well in advance of your arrival. The restaurants will book up long before you arrive.