Super cute quilt! Whatever you do is going to look great. It this was my quilt, I'd SID around the large blocks to lock it all in place and then I would do some kind of FMQ inside the squares. I'd leave the sashing alone, or do a couple of straight lines running down the sashings. Those lines would intersect and would look good I think.

Make sure you post again once its finished. Can't wait to see what you decide!