I, too, like my backings to coordinate with the tops. If I have not bought all the fabrics at the same time for a quilt, I will usually take the completed (or mostly complete) top with me while I shop so I do get a fabric that works with the top. In lieu of that I will at least take scraps from the top so I have a clue what shades work best. Then again, you get a specific color in your head and can't find what you want.....