I've done two just lately that I loved. I do a strip, either vertical or horizontal, with extra pieces from the front. This stretches the backing enough to save some. And I love the interest that it adds to the back.
I also love the wide batik fabrics (106-108" wide). MaryJos in NC had it for right around $13 a yard. I have also used that so there is no seam at all.
But I really do like the simple piecing the best!