Great input! For me, I try to keep the backgrounds fairly simple and consistent (usually just a sheet...), but like Shell and Karen have both said, black or white depends completely on the mask. If I'm photographing something where the color really pops out, or where the detail is showed to better advantage, I use black, but otherwise stick with white.
On the other hand, backgrounds when I'm using models are all over the board. They'd probably be more "front page-able" if we shot against just white or grey "fashion" screens. But, how boring is that!? ;D As a photographer, I'd just get too bored; we like to theme our shoots a little bit crazily (circus tent, anyone...?), so the backgrounds fit the shoot, rather than attempting to "fit" any other given look. And, yes, drama, drama! :)
ALL of that being said, I intentionally do things fairly often that could be damaging to my business, because I prefer to be true to my artistic instincts and preferences. So. Take that for what it's worth. ;)