An international themed Christmas dinner would be a nice idea and something different. Decorations of Christmas from different countries would be nice to be used as centerpieces. A variety of ethnic dishes and desserts would be a nice surprise. Your guests usually expect the usual ham and turkey but this would be a nice twist.
We used to fill our entire table with hors d'oeuvres from morning until night. People drop in at odd times during the day and can still "share in the meal"!
Christmas dinner should not be about the actual food, but about the people that have come to enjoy it. So a wide variety of dishes is a good idea, with plenty of side dishes along with the main course. Serve slowly with lots of time in between.
pinecones for decoration
mashed roots (potatoes, turnips, carrots, etc)
cauliflower casserole
quiche
apple slaw
green bean casserole
turkey with apple and onion stuffing
chocolate trifle
pumpkin pie
pecan pie