Have you thought about a simple cross-hatch in the middle section.... in the ditch around the half octagons.. maybe a simple curly -que around the red border? With the new fabric pens could easily trace your center and outer edge patterns on. Quilting a piece can be the toughest choice. Might try tracing a few on some clear vinyl..setting it over your piece to see how it looks. Cant wait to see the finish! Its very pretty