We've always done German Christmas, which means opening packages on Christmas Eve. Christmas Eve/day food is sauerkraut, ham, homemade bread (ham and sauerkraut are put on the bread open faced style), and tater salad. It's meant to be early evening food to eat before everyone heads to the living room to start imbibing, watching the fire, listening to old timey kraut Christmas music, and opening gifts later in the evening.
The ham and sauerkraut starts slow cooking early, so it actually gets nabbed in bits throughout the afternoon. The family has been getting smaller, but the food is easy to adjust to any number of people, and is easy to turn into leftovers.