I searched pieced backings and looked at all the threads listed. I like the idea of the tube backing, and I bookmarked the links listed.
http://www.reddawn.net/quilt/backings.htm
http://www.quiltingboard.com/t-22690-1.htm
That second one is really wonderful....for all things yardage.
I do not want more than one fabric on the back. I like the look of just a plain back. I put a lot of work into the tops and the quilting and like a single color back so my handquilting can make a design on it. The one I'm making right now is going to end up queen size....around 100" square I think. I won't know until I'm done with it.
Maybe tubing with three lengths of the quilts is the way to go...then I'd have 132 inches...almost a yard wide than I'd need, but I'm all for building my stash, since I don't have much of one, and a full yard can make some serious binding too.