Sounds like the fabrics in the top will make it pretty heavy for some folks ( like me)...while cotton batting will help reduce the feel of the seams on the back of the quilt, it will also add a lot of weight. I think the fleece would pad the bulky seam allowances and still not be too heavy - since i don't like the bulk of folded fleece binding (as I've seen some folks do) I'd probably just use a raw edge with the fleece backing cut a little larger than the top, possibly with a wave blade for some interest, then double stitch around the edge of the top, leaving the raw edges to fray as they will...again, reducing bulk of folded seam allowances, etc.