Tommy:
Dave Wigler has me covered - this isn't nearly as much about "greatness" as it is about a "feeling" one would get playing the place, the excitement derived from such, as Bob Huntley said. And although I dug Shadow Creek way more than most people, Dave also nails that in his assessment also.
This whole thing is very difficult to quantify, and many thanks to Dave W. for trying. He and I seem to look at this exactly the same. Others have different takes, and it's all good by me... Talk about subjective - trying to say what makes a course a "grail" for any person encompasses what he loves about golf, his status in life, what he's willing to give up for golf... taking this WAY beyond just "what makes a course great." JMD states it very well for me in his line about how it all comes together in perfection. That's as best as anyone can sum this up, at least how I look at it.
One more question for Ed Getka: I share all these thoughts about love for Rye, hey the President's Putter intrigues me also and I've read just about all the Darwin there is to read... But I still wouldn't call Rye a grail. It's not that difficult to access, and at least for me doesn't have the "must see in one's lifetime" quality (as TOC does) to "overcome" this and make it a grail. I feel like if I wrote the the proper people, I could get on... and it's not that far off the beaten path, so I may well get there some day without trying too hard. Thus no grail status for Rye for me... If someone called me today and said I could play tomorrow, I'd ask if I could postpone till later when I'm there anyway! One thing going against this though is Shivas' love for the course... for a long time he called it his favorite in all the word. That does make me want to see it more than most other places... so maybe this is a grail after all?
This illustrates in any case why and how people look at this differently... and Ed's definitive, non-wishy-washy take is very valid, likely making more sense than mine.
TH
ps to Tommy - some day in person I'd love to discuss exactly what I find great about the courses I hold most dear, I know that's what you want, you've asked me for this one way or the other many times. I'd bet anything you and I are very close in how we treat this, although I'm sure you doubt that now. In any case,I've had enough already of being pinned down on here and trying to defend myself! So bear with me if I tread lightly for awhile.