I have always tried to coordinate my backing fabric with the front. Because sometimes you see both sides at the same tme. I really like the pieced back quilts that someone posted. I also like the idea of putting some of the quilt fabrics on the back. I think everyone should do what they like. I read that many quilters have had good results with muslin and it it so neutral, it would go with anything. Quality fabric will go to pieces if not taken care of properly.