Here's an idea based on an old favorite activity...
Create a "Chain of Blessings" that will decorate your christmas tree: using colorful slips of construction paper, have each family member or church member write down blessings that they have enjoyed throughout the year; attach the slips together to make a paper garland of blessing around the christmas tree.
If you've like to go the extra mile and create a chain that can be enjoyed and added to for many year you can make it out of fabric and write your blessings with a fabric maker. Here is a tutorial.
Chains like this are great because they can be made by all ages, can be a great "team" project, and the repetative activity can actually be soothing and calming cause us to sit and pause during what is supposed to be a reflective season. Have fun!