We don't do Christmas too differently now we have children. We've just added a few things that are child-specific.
Christmas Eve is our favourite day. We get up and have a late, lovely breakfast with things like fresh bread from the bakery (buy two loaves so we have one for Christmas morning too), sausages and bacon from the butchers, breakfast muffins, bagels, pancakes etc. We build a fire to burn and put on various things to bake, the aim being that the house smells Christmassy. The pudding has its long steam that day, I put mince pies in, do a couple of starters for Christmas Day and put something in the slow cooker like casserole or stew and once everything's at a point where we can leave it, we go and call in on various people. Several elderly relatives, neighbours, friends who are alone at Christmas etc and we take homemade truffles and cards. Quick, small lunch and switch off everything except the slow cooker and then we go for a very long, bracing walk. Either on the coast or in a local nature spot. We time it so that as it starts to get dark and misty, we can do the last portion of our walk with a lamp or torch and then we hurry back to the car because (we say this to the children but we used to say it way before we had them), the darkness is the sign that the magic is starting to happen, it's just hidden away and we need to hurry indoors in case we see something we shouldn't.
On our way home we collect Grandad and then the interested parties go with him to a carols by candlelight service. Usually, I go home and finish the stew/casserole, make something like an apple pie if I haven't got round to it, sort out any last bits and then collect people from church. In the evening we have dinner, the new pyjamas and a Christmas film we have always done too. Sometimes friends come round and we tell stories, play instruments, sing carols. We watch a Christmas film and that's pretty much it.
Christmas Day we go to my parents' so traditions don't extend much beyond lots and lots and lots of food, presents, more food, bit of television and nibbles, maybe some snacks and some treats.
We do have a tradition of letting a different person each year choose what we have for Christmas breakfast and then the rest of the family has to make it for them. Last year, DD chose English muffins and poached egg for example and the year before, DH chose pancakes.
Boxing Day we go to the coast and DH jumps in the sea for charity. The afternoon is spent with ILs and involves lighting a fire, exchanging gifts and eating only Christmas food. So it has to have been bought for the Christmas season (crackers, nibbles, chutneys, stollen etc) or the leftover meat (always a turkey, a beef joint and a ham so plenty of leftovers) and the only thing we cook is jacket potatoes and bubble and squeak. MIL buys a new game every year and we all groan and complain but we really enjoy it anyway.
We've added in new traditions as the children have grown up but the bare bones have always been the same.