Keep it simple. Kids can get overloaded with too many activities.
We do:
Advent calendar
One visit to FC
Caga tio on Xmas Eve (we're in Spain, its a Catalan tradition)
Xmas dinner on Xmas Eve, so Xmas day is calmer
Xmas day: open stockings on our bed, pancakes for breakfast (ds has a small frying pan in the shape of a gingerbread man!), walk dog, tree gifts, homemade soup and stuff for lunch, go for a walk (to a little town along the coast, they always have a massive sand sculpture of the Nativity, different style every year, always fantastic), we can play with any new outdoor toys (bike, scooter,vremote control cars etc), home for dinner usually saltimbocca and a Xmas film.
Between xmas and new year: not a lot! See friends, see family, lots of hot chocolate and panettone.
We might make biscuits. One year we went ice skating (cheap through PTA). We used to go to a big indoor kidstraveganza when ds was younger (toys, bouncy castles, painting, cooking, scalextric, cycling, robots, circus equipment...) but he's outgrown it.
One year we came back to the uK and did panto, Cristingle, ds was knackered by 25th!
What I remember from my own childhood is:
Stockings
Same decorations every year
Helping stir the cake and pudding, adding the sixpence
Making oranges stuffed with cloves
Advent calendar with pictures
Using the special bowl and plates and stuff for Xmas lunch and to hold the nuts and mint choc matchsticks etc - I still remember them.
Putting out pillowcase and carrot etc for FC and Rudolph.
What I have totally avoided is anything I have to buy especially: Xmas Eve box with DC name on, special plate for FC mince pie with DC name on, matching pyjamas, MF Elf on the MF shelf - we don't have time for that and we don't like the idea of FC constantly watching and judging etc, spying, not nice.
Don't forget DC need days at home to play with their gifts and, I imagine, days to see family. Chilling out is the best thing about Xmas! DS is off 22 December -8 Jan
that's a lot of chilling!