When I was at a quilt show a few months ago, I found myself looking at the backs of the quilts since a lot of them were hung perpendicular to the aisle and I could see the backs without touching the quilts. It seems like most of them had plain white backs on them. Which I found curious. I've never done a white backing, all of my backings have been with fabric that coordinates with the front, I guess because that's what I've seen in magazines and such so just always figured that was "the way" it was normally done.
So, what do you do and why? Do you do both, depending upon the purpose?