We just did Christmas week this past year and had ADRs for BOG and 50s Prime Time on the 25th. We ended up deciding to go over to DHS to see Osborne Lights and so we ate at 50s, which was great. BOG or Crystal Palace would be our choice for MK, but you also may want to consider one of the monorail resorts. We did the Cinderella character meal at 1900 Park Fare another night, and it's a good reason to see the gingerbread house and other decorations. Cali Grill in the Contemporary is also a good spot for dinner, and it allows a great view of the fireworks if you don't want to be in the parks. We ate there on 12/30 and watched the early Wishes.
We also did Minnie's Holiday Dine at Hollywood and Vine. Others bash H&V, but we have eaten there 6+ times and never had a bad meal. It was ridiculously expensive, but a good experience.