I really like Mom3's suggestion. But, I also like the idea of a "little" bit more color. What about doing a narrow piping in one of the brights between each of the additional borders? I used one in a challenge quilt for my guild. I was surprised how easy it was and how effective,,,for being such a little thing.
PS. I really like what you've done. Are butterflies appliqued on the crosses? Gorgeous!