pretty colors. Barb

My suggestion is the one you ended up with. The quilt is so striking, so beautiful in its colors and design, that a simple black border is all I thought it called for. No piano keys--that would make it busy ,I think. You have done a wonderful job.

I am jumping into the deep water here, but in my opinion adding the dark fabric right next to the 9 patches would take away from the 9 patches everywhere they are next to the border. I would choose one of the fabrics that doesn't touch the outside of the quilt top; from what I can see, maybe one of the reds. I would make a narrow border of that color then a wider one, to match the width in the 9P of that darker fabric in the 9P.

Very pretty and good luck on whatever you decide to do !

Border
 

Yes, keep carrying out the same fabrics to the outer border or do plain w/ applique between a nine patch on the corners plus one in the middle--depending on the quilt size. Very nice colors. Great job. Would love to see what the final quilt looks like, please share.

Great quilt..