Planning out the shadow quilt

Last night, I got it in my head that I had to start planning out my shadow quilt. It's something I've been thinking about for a while, but it's suddenly become important to do NOW and not put off. I am sure everyone gets that feeling sometimes! :-) I received a set of charms from Andover; it was the TicTac line by Kim Schaefer. All 48 colors were included in the charm pack, so it is perfect for a graduated color scheme. Now it's just a matter of deciding if I'm going to go strictly light to dark or if I'm going to sort the colors within each spectrum and try to put each color block in the order of the rainbow. To be honest, I'm leaning towards the second option. Here's a picture of the fabrics. It is my first arrangement of the colors. I am not completely happy with it. I am planning to arrange the shadow blocks in a 6 x 8 rectangle. I expect the finished blocks to be about 10 inches square. If you have any suggestions on how to rearrange these colors, please feel free to leave a reply.