For a character meal, I would suggest Tusker House in AK> I think that of all the experiences, this one makes the most sense because you have to eat while in a park, and the buffet here is really good. I also like 1900 PF for dinner in the Grand Floridian. The food is good, and the interaction with the Tremain Family is fun for the whole family.
One character meal I have not done but that seems to be getting good reviews is Minnie's Holiday and Dine at H&V. I peeked in the window when we were there in December, and the interactions looked very good and not rushed, and the characters in their Holiday finery were really cute. This one, or Mama Melrose (If it is still open) in DHS makes sense because you can get Fantasmic vouchers if you book the package, and you can have a nice meal in the studios.
You are going in December, so will you be seeing the Candlelight Processional while at Epcot? If so, consider the package. It is a little pricy, but it includes an appetizer, entree, dessert and beverage. WE ate at San Angel Inn, and it was delicious, and we got nice seats to enjoy the show. If your consider cost, Garden Grill (another character meal, but an all you care to eat, rather than buffet) is an option, and it is outstanding in terms of character interaction and setting. It is in The Land, and cost wise is one of the less expensive choices for the package. I think Spice Road Table was as well, but have no experience there at all.
I would book Be Our Guest Breakfast for a pre park opening in the MK. You can share breakfast there so disregad the cost per person, and figure two or three meals for 4 to six people. They do bring a pastry plate and if you are sharing it should be plenty. Then you get to see the Castle, which is well worth the visit.
ANother CS meal in MK that we likes was the new menu at Pecos Bill. It is tex mex, and we shared there as well. Two meals for three people was plenty of food.