GL Pease Odyssey.
I know that's not normally considered a holiday blend, but it absolutely is my "seasonal" winter/Christmas holidays smoke. Something about it just brings up those associations. It's even gotten to the point where I rarely smoke Odyssey except from Nov to Jan, just to preserve those associations. As soon as I fire up a bowl I immediately think of setting up the Christmas tree, hanging stocking, snow outside, blah blah blah.
Otherwise, my favorite holiday blends would be Autumn Evening and Exhausted Rooster. Autumn Evening always make me think of the Fall (a well-named blend, as I think of maple as a basic autumn-type flavor), while Exhausted Rooster has a topping that reminds me somewhat of egg nog.
Sorry if this isn't exactly what you're looking for. I've tried many, many "holiday' aromatics, and for some reason haven't found one that grabs me. And it's not that I hate aros -- there are several in my rotation. It's just that they normally aren't what I crave come the Holidays. In fact, I usually smoke them in warmer weather....