well, i think it looks lovely. i personally would just stop with the squares you have. as far as a border, my thought is three rows of SC (yeah, i know you said you don't want to SC, but this is my idea
) alternating colors, dark/light/dark, maybe even do the light row as a puff stitch. then maybe put some big tassels in the corners, or do a picot stitch around the edge. ok, those are my thoughts.