If you do the d9p I would use the darkest blue for the centre square of the 9patch, a medium blue for the four centre side pieces and a light square for the four corners. I think they always look more striking with this configuration as the larger squares then appear to 'float' over the smaller squares and rectangles that emerge. If you're planning to use more than 3 fabrics, I'd sort them into three groups by colour value, ie dark, medium and light and place them as I suggested. I think it would be beautiful. :-D