Great question. I think it's going to be a matter of personal preference more than anything on how each of us does our backing. As for me, I am still a fan of muslin. I often use top quality muslin for my backing. I get so many compliments on the quilts I give as gifts that the back of the quilt is so soft and comfy when they snuggle up under it. (Most of my quilts are lap quilts.). If I don't use muslin, I use whatever neutral fabric I used in the quilt top for the backing. Either way, I just piece together whatever I have to make the back big enough. Because it's all the same fabric, there is no pattern to the piecing. I just need to make it large enough.