The very first quilt I ever made was the one above, from Elizabeth Hartman's tutorial at Oh, Fransson! (Sorry for the sun glare on the photo of the back.) As you can see, I followed her instructions to the letter, right down to the fabric selections. I appreciate that with many of her patterns, including this one, she provides instructions for a coordinated, pieced back. Gina mentioned Elizabeth's Craftsy class on "Creative Quilt Backs," and I'd also highly recommend her patterns and books. The quilt below uses one of the patterns from her first book, The Practical Guide to Patchwork (Stash Books, 2010). Out of sheer frugality I pieced together solids from my stash for the bottom section of the back, but the overall layout for the back, including the pieced strip in the middle, was part of the pattern. All the cutting and piecing for it came together while I was completing the top. For both of these quilts, it was great that by the time I was finished with the top, I was almost finished with the back, too!
When left to my own devices, I usually just sew together two matching pieces of yardage and call it a back. It's quick, and I'm finally making backs for some of those quilt tops that have been languishing in my closet. I was afraid it was a terribly boring practice, until I made this Berenstain Bears quilt for my son. He likes the print that's on the back so much, he always keeps it wrong-side up on his bed!