I'd be tempted to ditch around the appliqué to make it stand out, then following the direction of the the light and dark lines in your background I'd do some matchstick-like quilting with either a 100wt. silk or poly in a matching color, or using an invisible thread. The matchstick quilting would give the background texture that is like the visual texture it already has and would flatten it more which would allow the organic shapes of the butterflies to stand out.
Beautiful quilt!!!
Rob