OK, just another opinion here. A piano key border may distract from the star patterns. You have made a bold move to make this traditional pattern in tropical Caribbean colors and it is lovely. The border you are suggestions might be very "busy" and distract from the stars. As others have so gently suggested perhaps just bind it as is or if you need to make it a little bigger, choose one favorite color and go that direction. You could always do a scrappy pieced binding.