I love the idea of taking the same photo each year during the holidays. That way when years have passed, you can look back and truly see the growth and progress.
This year, why not place your kids in front of the tree and snap away. Then repeat each holiday until they are raised and educated and married off living away with kids of their own.
Then print each shot and make a coffee table book that you can leaf through during your holiday party. Memories to last a lifetime.