Wow! Stunning quilt!
You probably want to highlight the center medallion...thus quilt the print surround it, and also the wide border of the same fabric. Something swirly in the wide outside border.
SITD around the narrow borders, and the next border out from the medallion. Also SITD around the large squares and the diamonds in the center of each side. I can't decide if you should quilt the smaller squares that are towards the outside. Probably do something more detailed there?
Have fun deciding!