Stockings downstairs in the Living room.
We do a Christmas Eve Hamper after dinner - DD is very excitable (takes melatonin to get to sleep level of excitable!) and needs routine so even though she's now 14, we still do this.
TV goes off when we start dinner and doesn't go on again until DD is in bed. Instead, we have either radio or CDs/spotify etc going in the background.
Dinner is a "platter" - a spread of lots of nice cold things (and occasionally a few hot sausage rolls or similar) in the middle of the table for everyone to help themselves. Cooked and cured meats, seafood (prawns, squid rings, smoked salmon), cheese, cherry tomatoes, olives, carrot and pepper sticks, hummus, salsa, breadsticks, pate, salad leaves, etc. (Not everything every year - just a nice spread of things we enjoy, including a few special treats). Very simple (cos you serve yourself) and relaxed.
We go into the sitting room where the tree lights and reading lamps are on but not the main lights - pleasantly low level. Youngest (DD) lights the Christmas Candle (to show that there is "room in our Inn for any weary travellers), and we have a few minutes as a family to remember the good and bad things that have happened in the past year and remember those no longer with us.
Then we pull out the large shoebox sized box that holds DD's Christmas stocking, her plastic Santa plate and glass from toddlerhood (used all December until tree comes down and it goes away with decorations), her snowman covered hot water bottle (used all winter), family copy of "Twas the Night before Christmas", new pjs for all, lush festive bath bomb for her (and a very relaxing one for me), nice hot chocolate for everyone and a Christmas beer for DH.
DD puts out milk and cookies (that she baked in the afternoon - sometimes from scratch, sometimes just sliced from a pre-frozen half batch from earlier December baking) and lays out her stocking in the sitting room. She heads up for her bath and into fresh pjs. Comes back down for hot chocolate (no hot drinks in the bedroom rule) and a snuggle, and then I used to read the book in bed as she was tucked up warm and snug with her hot water bottle - but last year, that was abandoned and she read it to herself.
She is still excited, but it does help to settle her down.
Lush's IckleBot bomb is great for DCs and filled with lavender which can help sleepiness.
We also use lavender pillow spray at times, the hot milky drinks, lower level lighting rather than harsh bright lights, …...all sorts in general to help get to sleep. But because it is a calm, relaxed night all evening leading up to bed, Christmas Eve has generally tended to be one of the better ones in the calendar despite what it was leading to (and her birthday is 26th so a season of excitements!!)..