I love Christmas!
Dave and I are stupid with the amount of holiday movies and music we've collected over the years. I'm not kidding. It's gone from the sublime to the ridiculous now. But you know what? That's cool because we've started our Christmas ritual that begins somewhere around Thanksgiving and runs until Christmas night. We watch a couple of movies a night (one of them always some version of A Christmas Carol, since we have about 7 or 8 now - maybe more.) The tree goes up on my birthday, followed quickly by the packages. (Can't have a tree without wrapped packages underneath.)
But I don't just celebrate Christmas in my real life, my character sketches are full of families with different holiday traditions. I think it helps to solidify and cement a character with rituals and traditions. Even if they aren't like my own. Especially if they aren't like my own. I have one character whose family goes to Vegas every year to celebrate Christmas because his parents eloped to that city around Christmas time years before. Thus they all return to have the holiday there. I have another family who go to a ski resort for the holidays. Still others are more traditional celebrators with the big Italian Christmas Eve fish dinner then Mass afterwards. I even have some characters who don't observe the Christian holidays. They celebrate Hanakah or Yule instead.
I don't think it matters what holidays your characters celebrate, if you've made up your own in a fantasy world, or if you decide to have your character reject them, it helps to make your heroes and heroines more realistic and bring them to life in your prose.
Have a safe and happy holiday season everyone!!!