If I were using backing fabric for the large quilt, I would buy the best quality that I could afford. Being a longarm quilter, I have seen some beautiful backings that were so crooked and stretchy, kinda like the $1.50 stuff at Walmart. clients bring me a beautiful top but bad backing. Doesn't look nice when quilted, even puckers sometimes. I found some really nice backing from fabric.com and also connecting threads. JMHO.