Wow, that is stunning. I would think about continuous curves on the cross seams of the pinwheels so it looks like flower petals. A flourish at the center of the NYB block with SID around the the narrow bands and spikes. In the corner piece I would do a half feather to fill. First I would draw it out with a dry erase marker on a big piece of vinyl or plastic placed over the quilt to see if I like it. I tried to draw it out on a picture of the quilt, but my drawing ability on my computer just stinks.