What does a rationalist do for Christmas (or whatever analogue is going on around you at this time)? Stay at home and grumble, "Bah, humbug! Stop having-fun-for-bad-reasons, and did you know that Láadan has a single word for that concept?"?
Attempting to light a candle instead, I am giving my teenaged nephew, who was into science but is now into history, "Guns, Germs and Steel", which combines both. Someone else (I haven't decided who) is getting "The Atheist's Guide To Christmas" which has chapters by Richard Dawkins, Ben Goldacre, Simon Singh, and the like.
What are you doing for Christmas?
People have been celebrating around the solstice long before Christianity sold the holiday. Most of the Christmassy things: gifts, trees, fires, food, song and so on are left over from pre-Christian holidays. Take back Christmas a have a ball.
I just think it is a good time for a party and has been for a long time at high latitudes. I don't think there is a problem with this. If religious people want to control the party, just ignore them and enjoy Christmas.