Priceline.com looked at average airfares for the dates leading up to and following Christmas (based on ticket purchases made by its customers) and found: the most affordable days to take-off right now are December 14, 15, 18, 19 and 20.

Good, but not the best days, are December 21, 25, 30 and 31. While tickets on these dates might be cheaper, they certainly aren't cheap.
Priceline also found that the average airfare for Christmas is currently $451, up 3% from last year.

Are you going anywhere for Christmas? We don't travel at Christmas, it's too wonderful here!