I'm one of those who wants the WHOLE quilt to look coordinated. I have had to sew two pieces together to make it wide enough, but it's the same fabric, and typically matches some of the fabric on the front.
When viewing Trunk Shows at my Guild, I'm always disappointed when I see the back is just random squares and rectangles of all sorts of non-coordinating fabric. I make mostly lap quilts, so the backs and fronts are both seen, and I want the continuity from one to the other.
Mine are mostly for charity, and I want the recipient to know that I took the time and trouble to make it "nice" for them.