First of all, beautiful quilt! Now to the quilting...... after reading the other posts & going back & studying it again, I don't see using gold thread. I think it will overpower it. What batting are you going to use? Look at the stitch distance for the batting. If you can get away with it, I'd just outline the 1/4 circles. Like you would go around applique. Definitely SITD all of the sashings. In the sashings you could do a small pattern of genko (?) leaves. There I think you could get away with the gold maybe. I think larger leaves in the border would tie it all together. Maybe a light stippling in the black & white area with their respective colors too. I know, a lot of thread changes for each pass, but worth it in the end.