you've picked the 2 parks with the least options for character meals.
AK has Restaurantosauros which is a breakfast buffet with Donald Duck
Epcot, there is the Garden Grill, or a princess character breakfast in Norway, and I think that's it.
I think for Christmas, I would probably go to the Liberty Tree Tavern in Magic Kingdom - that's the place that feels most like Christmas to me. Dark wood, turkey to eat etc etc. (Bouncy guy is for my dd)
I am sure that I read that Restaurantosauros are doing a special christmas themed character breakfast which would be perfect. This is the first year of it but if you phoned WDW Dining they would have full details.
Wendy
Yes Wendy's right, the Restaurantasaurus in AK are holiding a Character Breakfast 'Deck the Halls with Donald' which also features Santa Goofy. I rang to book this a couple of days ago for Dec 28th and the agent didn't have any details about the special Xmas version, so hopefully it is going to happen, but I will be checking the DIS Restaurant Board in December to see what is actually being offered.
If you are interested in this, I wouldn't hesitate in booking it, as it is a very popular breakfast any time of year, you can always cancel if you change your mind.