Holidays are for kids and grandparents. If you're a member of the generation in between, your job is to make the holiday as enjoyable as possible for them, biting the bullet (and your tongue) if necessary. If your son and your parents have a good time, you can feel satisfaction for having done your job well (and you can feel justified in rewarding yourself later by doing something you REALLY like).

Sorry to sound cynical, but it has worked for me (my youngest is 18), and sometimes you find unexpected rewards in making things nice for others.