When I was a kid:
Big family party on my Mom's side was always the Sunday before Christmas. Presents for little kids, but teens and adults would do a "small things" name draw way back in summer, so you had tons of time to bargain hunt - because you were only allowed to spend $5!
My grandmother on that side also always strung candy canes through her living room. The strings would go wall to wall, and taller folks had to duck under them, but you could just pluck one off whenever you visited her. She was always kind of the "stuffier" grandma from my kid point of view, but her whimsical side came out full force at Christmas!
At home, we were (like many others said) allowed to open one present Christmas Eve, and we always had homemade soup for dinner, and "shrimp stuff." (Spread cream cheese on a plate, mix tiny shrimp and cocktail sauce, and pour it on top. Serve with Triscuits or Town House crackers.)
On Christmas morning, we could only wake Mom & Dad up
after we turned on the coffee pot!
We could open our stockings while we waited for it to brew, then we all did presents together, and
one at a time - none of the "feeding frenzy" you see on TV! We took turns and all watched each item get opened.
Dinner was at my grandmother's (on Dad's side) when I was really little, and then my Mom eventually took over at our house, and it became buffet style.
With my family now:
Have continued the one gift on Christmas Eve (see below) and the "shrimp stuff".
Some evening a few days before Christmas, we all drive around and look at lights. There used to be one of those walk-through displays in our town, and we would include that as well.
When DS was little, we'd go to the 4:00 Children's Mass on Christmas Eve, and then afterwards there used to be a big neighborhood party. We would all slip the hosts one of our kid's gifts ahead of time, and "Santa" would leave a big bag on the steps and make a bunch of noise (but of course never get caught) and they got to open that one early.
Cinnamon rolls for breakfast Christmas morning. Slow gift-opening, and then "A Christmas Story" on TV until it's time to leave for MIL's (only 20 minutes away.)
Early Christmas dinner there, with lots of family (frenzy gift-opening) rowdy board games after dinner, and
sometimes karaoke on the TV.
The three of us started a tradition a few years ago of a movie on the day after Christmas. We've found it's really nice to have something to look forward to, because otherwise that day is such a let-down.