We always spend Christmas Eve in Epcot, ending the day with the Candlelight Processional. On Christmas morning, we sleep in and either hang out at the resort or head to Downtown Disney for a movie/bowling/DisneyQuest afternoon. We've always gone to the Magic Kingdom in the evening, usually waiting until around 8:00 p.m. or so to arrive. In fact, when we had to miss Christmas in Disney in 2013 due to my back surgery, we missed the carefree time spent at Disney. It was nice to just focus on family without having to worry about the obligations of home.
We always end up at the Magic Kingdom to end our Christmas Day. When the kids were younger, we'd head to the park mid-morning, ride some rides, and have a table service before returning to our resort for the busiest part of the day. Over the past several years, however, we opt for a very late breakfast in the resort or lunch at Downtown Disney. Then we have a late table service for dinner in the Magic Kingdom.Last year, we scheduled the Tomorrowland Terrace Dessert Party for Christmas night, and it was a great way to start our evening in the Magic Kingdom.
Since we drive down, we've always taken a small tree with us. Along with window clings and Command hooks for our stockings, our room is filled with Christmas cheer. We pack Santa gifts in the car (or did until our youngest figured it out...on Christmas Eve at French Quarter no less) and purchase stocking stuffers at MouseGears or World of Disney. The kids still purchase gingerbread men for Santa at Epcot on Christmas Eve. They were bummed (as was I) when the gingerbread house was missing from the American pavilion last year.
Spending Christmas/New Years at Disney has spoiled us for everything else. We book the upcoming year on New Year's Day.