Judy, I have done a little bit of everything with quilt backs. I really like this idea though.

My SIL invited me to her quilt guild several months ago to hear a specific speaker (can't remember her name) but she does fairly modern, abstract-type quilts and always includes some of her extra fabric on the back . . . whether it's a block, something patchy, or even words pieced into a strip.

Go for it!!