mine are older, but we have developed some great traditions....
make and ice cristmas cake - it doesnt matter if its garish pink with 100 sugary characters on top. They will love it.
We have a tradition of putting up our tree the first weekend after DDs birthday (mid dec) where each person has their own particular items to put on the tree in a particular order -dad does lights, I do tinsel, kids do baubles, then there are specific ornaments - dd does Mary, DS does Joseph, DS2 does Baby Jesus, they all do 3 kings, DS does Star, DD does angel. DH and I get quietly sloshed while this is going on...:D
We have an ELC nativity set of little plastic figures,which now also includes a fischer price "granny" after it was added lovingly by DS2. Now Granny has to attend the nativity every year too. 
We go to Panto on Xmas eve. Always great for getting us all in the mood for Christmas. Then home dinner - usually a chicken and rice dish which is a family favourite. And a big sloppy pudding.
Then we play cards until about 9:30-10ish - newmarket, 5 crowns, rumey etc.
Noone is allowed out of bed until 7am. Then they all pour into our room and sit on our bed to open stockings! Every year, there are predictable items in the stockings.
Pressies are doled out one by one after breakfast by DH so we can all see what everyone has. If kids start to get bored, we halt proceedings so they can play with the toys they have received thusfar. This means pressies can go on all morning.