I recommend trying for reservations NOW, especially for some of the more upscale options. But the list is pretty big and it will get bigger, so do check back if you can't find someplace that works for you.
Here are my picks from the list as it stands right now:
Bull & Bear at Waldorf Astoria Orlando: Four exceptional courses, served from 5 p.m. to 10 p.m., at $105 per person. Wine pairing is also available at additional cost. Reservations required: 407-597-5409.
Emeril's Tchoup Chop: Enjoy an Emeril-style Christmas meal created by Chef Ryan Vargas offers a Christmas meal a'la Emeril, which is my favorite eatery of any at the Universal Orlando hotels.
Café Osceola at Rosen Shingle Creek: This my best pick for a holiday buffet. Over 44 dishes will be offered, including holiday favorites, carving stations, desserts galore, and unlimited champagne mimosas. It's served all day long on December 25, from 11:30 a.m. to 7 p.m. Cost is $65.95 per person or $29.95 kids (4-12 yrs. Old); kids under 3 years old eat free. Plus complimentary valet parking and a 25% discount for Florida residents.