In an article on color Weeks Ringle also used a Gray Brown as a neutral for tone on tones. This made me think of walking through fall leaves and how the bright colors pop against the Gray/Brown of the ground. The blue is a good idea too. Think of maple trees against a clear blue sky on a sunny day. NOTHING more beautiful! It would be a very colorful quilt so that would have to be the look you are wanting. Let us know what you decide.