unappealing as this sounds - how about a light/medium gray or greyish tan or tan?
I went to the Quilt Museum in Paducah and, if I remember correctly, the walls were sort of one of those colors. Definitely not white.
I also read in one of the quilt books - sorry, don't remember which one- to use a tan or gray - that way the contrast is less intense and it's easier to focus on what you have put on it. I'm thinking it was a Kaffe Facett (I know that is spelled wrong) or a Jinny Beyer book.