I was there for a weekend and wanted to maximize my time. I highly recommend taking a bus tour to see everything and there are sooooo many to choose from.
It's great to have a guide to tell you about the country and some history or interesting information about what you're looking at.
Things are really far away from each other, so there's a lot of driving to do. Riding in a bus is a lot more relaxing and less tiring, and they left us plenty of time to visit each spot. (anywhere between 20-45, so they're usually more than just drive-bys!)