I saw Old Head before anything was built. A stunning site, but I certainly had some question about whether there was enough room out there to build a great course, so I would disqualify it as a great site.
Ballybunion was recently soliciting proposals to work on their New course, and I went and looked at that, but decided not to touch it. Partly that was out of respect for Mr. Jones [who believed it was the best course he ever built, even though I would not agree], but I did try to figure out a way to get a better routing than what they have and couldn't ... the site is just too severe. [So, Paul, you need to get over there and show them what you can do!]
The only site mentioned so far which I think was a really great site is the land for The National in Australia. I worked on routings for it, too, a long time ago, and thought someone should get at least an 8 or a 9 out of it ... they think they got a 10, but it doesn't count if you add the two courses together.