The holidays are a great time to introduce family traditions. One tradition we started at our house involves Christmas books. At the end of the season when I'm packing up all our Christmas stuff, I find all our Christmas books. I wrap them in left over Christmas paper and pack them away in a box. At Christmas time the next year I pull out the box and put all the wrapped books around the Christmas tree. Each day for the month of December the kids each take a turn picking a book for the day. They open the book and then we read it together or the older kids who can read will read it to us. It's so much fun when we're getting out the Christmas decorations to see a whole box of wrapped books! We have no idea which books are where (a year is a great thing when it comes to forgetting!) and it's exciting for the kids to open up a book. I might get a new book through the season and wrap it as well. This is an inexpensive way to fill your tree with gifts you already have and provide specific reading time at night!
Another tradition at our house involves the Advent Calendar. (On a side note... has anyone else noticed these are getting harder and harder to find each year? Please tell me stores aren't doing away with the calendars!) I probably have almost 10 advent calendars from the past 10 years. We save them and use them each year. The kids enjoy each picking their own calendar for the month. Each morning before school (if there's time) they'll open up their day and read it to us. If it's too chaotic in the morning, and it frequently is, we'll read it at night.
I know we have lots more traditions than just those two...decorating the tree, making and decorating cookies, gift for their classmates that we make, watching certain Christmas specials, etc. but these are two I really enjoy.