At my office, they began playing Christmas music two days before Thanksgiving and they probably won't stop until after Christmas--or when I take an axe to the CD player.
Still, there are a few Christmas songs that I do love to hear:
"The Christmas Song" by Nat King Cole
"Christmas (Baby, Please Come Home)" by U2
"Gabriel's Message" by Sting
"Rudolph, The Red Nose Reindeer" by The Temptations
"This Christmas" by Donny Hathaway
The various songs from the Charlie Brown Christmas