DS1 has asd and gets stressed by too much going out and excitement. So ours tends to be low key and predictable from one year to the next but still fun for the other kids.
I usually kick off with a forest walk to find pine cones etc which makes for an afternoon of crafting a day or two later.
We carefully compose our letters to Santa and post them
We have various baking and making days: the gingerbread house and stained glass cookies are a tradition.
And we do some art and craft things too. Much planning and discussion bickering and squabbling goes into these
We decorate the back windows with snowflakes and the floor with confetti
Writing cards to everyone
in the class is an obsessive one that has to be spread out over several months
so I've learned from painful experience to start that in October
Decorating the tree is a big day too, and both sets of grandparents need help with theirs too so that's another two evenings.
Dragging all the boxes of crap precious decorations out of the attic is an evenings activity too
I try to take each child shopping separately for gifts they want to buy and then we go for cake and coffee. It can be tricky to organise the childcare but they love their special mum time 
And we have one food bank shopping trip too.
We make bird feeders and fat balls and decorate the trees in the garden.
And take a trip to the park to feed the ducks and the aggressive dive bomber seagulls
And we visit the most wonderful Santa Claus ever.
Any other outings I save til after Christmas. By then boredom has set in, and everything is more low key, the crowds are less intense and I'm focused on the kids and not distracted. There's trips to the ice rink, a show with dd, rides on the Christmas train at the local shopping centre and visits to cribs. And more feeding of ducks.
It all has to be fitted around homework, dinners, after school activities, therapy work and playtime so while it sounds like a lot it's generally 20 minutes or so here and there.
I'm a little envious of some of your outings and excitement but still we enjoy the build up albeit in a very homey way and hopefully without meltdowns