I don't see any blue in the quilt. Are you going to hand quilt or machine quilt?? That usually helps me select a backing. If you are hand quilting it, I would use the same fabric as the background so you hand stitches would show. Otherwise, I would go looking on the internet or your LQS for a coordinating fabric that would coordinate with the fabric you used in the front. Your daughter is going to treasure this quilt probably for her entire life. I would use the same fabric in your sashing for the binding too.