Wow, so many to choose from! We do lots of things each year here!
I will have to say the new-ish tradition (a few years now) of celebrating Christmastime instead of 'just' Christmas Day.
From the day after Thanksgiving to New Year's Day, we celebrate Christmastime. It involves the spectrum of traditions and fun we all enjoy: decorating the house, watching the movies and specials we all love, listening to Christmas music, having friends and family over and, in turn, visiting family and friends. We also take one night to drive around and look at the lit-up houses around town.
Our Christmastime is non-religious, it is just about enjoying the time together and celebrating the warmth of family and friends.