When my children were growing up, I always had Christmas dinner on Christmas Eve. My parents would attend and my brother and his family if they were in town. I would make the dinner very special with candles and etc. It gave the kids something to look forward too on Christmas Eve and it helped make the evening go by quicker for them.
The plus for me was that I got to spend Christmas Day enjoying my kids and not in the kitchen. If anyone got hungry, leftovers were heated up with very little fuss and bother.
Today I still do it for it makes it easier for my married children to be fair and spread their time between two sets of in laws.
Hubby and I have spent many Christmas mornings alone since the kids have grown but we still play the Christmas music and open our gifts to each other. It's a very special season in our lives now and we enjoy it being just the two of us now. And eventually the phone starts ringing, our children calling to wish us Merry Christmas.