On the long drive back to Reykjavik, we stopped in Kirkjubæjarklaustur for dinner. We totally lucked out and had an amazing meal at incredibly reasonable prices. I would highly recommend Systrakaffi for anyone traveling the ring road.
I did make a serous mistake in our itinerary. I planned on day outings, with evening in Reykjavik. This is insane when you're trying to drive 760 km in one day, and stop and see things, and hike. So far we've gotten back to Reykjavik too late and too exhausted to do anything. It would have been much wiser for me to end our day touring the Golden Circle in Vik, do Jökulsarlon the next day, Vik the third day, then head into Reykjavik for the rest of the week.