If you used the piano keys border you would create a 'heavy' feel to the outside of your quilt that otherwise has a 'light' feeling because of the use of so much white. If, on the other hand, you used the idea toverly suggested you would continue the 'light' appearance. I think I would make a small section of each idea and audition them. But, please don't forget to show us what you choose. Your quilt is very pretty.