The Saturday Post: Sounds of the Season edition

Thanksgiving is over so now, finally, it's acceptable to start the holiday music. Each Saturday Post between now and the big day, I'll feature videos of some of my favorite holiday songs, sung by those I think do it best.

To kick things off, here is the preeminent Christmas voice singing, of course, "The Christmas Song":

Today's question:

What's the best song for putting you in the Christmas mood?