usually the quilt decides what i use for the backing; sometimes i piece a back with different blocks of fabric, sometimes i buy wide fabric, sometimes i use minky or fleece...it just depends. i use what ever i need to at the time...never buy 9+ yards of fabric for a back though...i'm afraid it would get cut up and used for a block before it made it to a quilt back. if the back is not fleece, minky, or 108"-116" wide...i piece a back.... as in multiple fabrics pieced together till it's big enough.