I've started just going into my stash and using things up to make a backing when it's not critical to have a fancy back. It seems like a good way to get rid of things I never seem to find a place for on a front but that do kinda "match" for the back.
The simplest scheme seems to be to put them into big fat stripes going the width of the quilt.
Then I have more room to buy fabric I really like.
Susan K see my quilts: members.cox.net/kratersge