A lot depends on what I'm quilting. If it's a larger quilt, I prefer the extra wide fabric so that I'm not spending extra time piecing it to", gether. Solid colors will show all of your quilting stitches. The good, the bad AND the ugly. My preferred backing fabric is a creme colored floral print because it's neutral and doesn't try to compete with the front. If I'm making a child's quilt that is just a little wider than 40", I've made a cut in the backing fabric and added a strip of leftover blocks. Just don't try to add the strip right in the middle. Do it about 12-15" in from the side. That way it looks more like an intentional accent piece, rather than a patch to make it bigger.