I get asked a lot of questions about quilt backs, pieced backs in particular. There is a lot more thought going into quilt backs now than ever. My requirements for quilt backs are that they need to be bigger than the quilt top by 8″ wide and 8″ in length after you’ve squared them up.
I also request that you do not put a border around them or “picture frame’ the quilt back. Even with the best plan, the quilts can draw up during quilting and result in a bottom border that does not match the top. I would also try to limit the amount of piecing around the outer edge of the quilt back as clamping may pull piecework apart ( ex: piano keys). Stay stitching around the edge can help to prevent this but limiting the amount of piecing near the edge is a good plan.
I do love the look of pieced backs & there are so many great ways to do them. I found a great free instructional online video that shows several ways to piece backs. http://www.craftsy.com/class/creative-quilt-backs/117 You will have to sign in with http://www.craftsy.com but it is well worth doing to see some of their free videos. Elizabeth Hartman also has a blog with free quilt patterns you may enjoy. http://www.ohfransson.com.