Man, I would LOVE to have a heavy quilt like that on cold nights. I get too hot to quilt something that heavy though. LOL
I agree that stitching around the squares or crosshatching would be fine, and it'll look great on the back, too. Just make sure you have sturdy thread and the right needle. Also be sure you are sitting at the right height and plan to take breaks because shoving that baby around under your needle is going to be a work out.
Welcome to the QB, and congrats on your quilt! It looks fantastic!