First stop out of the airport is the famous Blue Lagoon. It may be a cement-bottomed tourist trap next to a geothermal power plant, but it's convenient to the airport and, as Erik's first visit to Iceland, it's hard to complain as the very first stop.
Saw Fagradalsfjall Volcano erupting in the distance as we drove to lunch but elected not to stop. Ended up very decent deli complete with a tasty lobster bisque, then off to see a ton of waterfalls. Walking behind Seljalandsfoss was kind of cool, and the narrow canyon containing Gljufrabui was barely a minute's walk down from the same parking area, so well worth the stop. Not far down the road was Skogafoss, with a few more waterfalls up the path as well, also kinda cool.
Spent the night in Vik, complete with an artery-clogging dinner of burgers, onion rings, fries, and beer. Probably should have skipped the fries and onion rings, but the hefty burger was a welcome sight.