I always like to add a small sash as well as a border to keep all the seams from coming apart while quilting it. It also in my opinion frames the body of the quilt. You could add a small white sash and then use one of the fabrics for the border. Doesn't need to be very wide of a border either. Using the piano keys quilting pattern is a great idea unless you meant to use pieces of fabric to create a striped effect for the border. That may take away from the body of the quilt as the person might not know where their eyes should be looking at with so much going on.