I'm not sure how heavily you plan to quilt them, but I'd be tempted to use a very simple pattern. You could use painters tape to get straight lines to follow for crosshatching, straight line quilting and stitch in the ditch. Alternatively you could draw your pattern onto paper like Golden Threads paper and then pin it to your quilt top and stitch through that - if you choose this idea, I'd only pin one piece at a time.