How about an easy star in the solid blocks and a swirl in the borders? Consider doing a cross hatch over the embroidery. I know it sounds like it would over power the stitching, but if you match the color of the thread to the backing, all you will see is the texture of the cross hatch. If you do no stitching in those blocks, you run the risk of it 'poofing' up. For the border, how about a piano key border? It sounds too simple, but it really looks nice.