As much as Christmas has become a secular holiday of both commercialism and general charity/goodwill/family togetherness, which is fine, I think it would be a sad, incomplete December 24 without a visit to Mass. I dread the Easter Mass in my arrangement with God, but the Christmas one is wonderful. (I've blogged about it before, but now there's a possible Amazon gift card riding on it so it gets a second look.) Attending the evening service is not really like attending church, it's like being part of the theater. Even though it follows the same base structure as any other week, it feels different. The decorations are beautiful, the readings are like being told a comforting story by a relative, and you get to sing all your favorite songs. There's also something about going at night, as opposed to morning, that makes it feel magical.
Of course, I also celebrate Christmas for all the other awesome traditions such as a tree -- my family has hundreds of ornaments, too many to fit even on our huge tree, from the 1930s to present day -- stockings, Nativity scenes and Santa decorations (this is the only holiday we really decorate for, but it is spectacular inside), and presents. And getting caught up in the national celebration of it all, too.