Personally I feel that the quilting, while it can enhance greatly, should not compete with, but compliment, the quilt itself. You have a beautiful quilt made and I think you would distract from the overall effect if you used colors in the white area. I have seen award winning quilts which, the more you look, the more you see. At first most of us don't see the quilting, but upon closer inspection it is a thrill to discover the beautiful designs quilted in. It makes the quilt a venture of discovery.