Growing up, Christmas Eve meant going to our church Christmas program, followed by the large family Christmas party with all my cousins/aunts/uncles/grandparents at my grandparents' house. Most of the extended family came to our church on Christmas Eve because it was so close to the house, and we enjoyed crowding in to the small church with all our family.
As the family expanded and grew, and the grandparents passed away, that faded off. But, Christmas Eve has always been close to my heart.
My husband and I (and our children when they are in town) have recreated a version of this by going with my parents to their church on Christmas Eve (the same country church we attended when I was a child), then having a quiet evening at their house with simple appetizers/snacks/sweets. It's still my favorite part of our Christmas traditions.
This year my sister, BIL, and nephew will be here (from their home in Florida) so we'll have a bigger group for Christmas Eve.
Christmas Day has always been very quiet. Just our own family unit at home. Our big meal is breakfast, followed by gifts, then just some sort of simple comfort food for a late lunch/early dinner. When the kids were small, the grandparents would sometimes pop in for a few minutes to see what Santa brought. But no parties or elaborate meals.