I finally found the competitive difference between Borders and Barnes and Noble. B&N is much larger, at least in downtown Seattle, and has a larger stock of half price calendars left over from Christmas. After striking out at Borders, I was able to find two calendars that fit my needs at B&N. I got a monthly "kitten" calendar, but it's black and white, so I can pretend that it's art.
I thought I would have to resort to posting my Lil Sis' calendar. Don't get me wrong; it's a hilarious calendar; it just isn't (remotely) safe for work. I think it'll do for the home office, though. I particularly like the "Febuary" cartoon.