Money Christmas Tree
Disney Theme Christmas Tree
Football Theme Christmas Tree
If your family has a large interest into one thing, whatever that one thing is can be the theme for the Christmas tree. The rest just take a little imagination. For example if your family likes to go hiking you can make the Christmas charters go hiking. Add little hiking sticks and shoes.
Overall it doesn't matter what you decorate the Christmas tree with as long as you and your family like the Christmas tree. Just remember to be safe.