We were in Olympia last summer and I got a private driver from TripAdvisor to take us wherever we wanted. I loved the Ancient Olympia Archaeological Site. If you do it without a tour guide, I recommend you do the museum first because it gives you a good overview of the layout of the grounds to have a better idea of what you're looking at. The site was cool because it mostly hasn’t been restored so you can see lots of the pieces where they fell after earthquakes, etc. We also went to the Koufolias Olive Oil Mill and learned all about how they press the olives to make olive oil. It was fascinating. We even got to do a tasting. Highly recommend!