Mike,
I still think the first volume stands out for me.
Geoff's "Does it tempt?" to this day is one of my favorites.
Mark Parsinen's "A sense of place in course design" describes the difficulty in striking a balance between staying true to the land and following your vision.
Todd Eckenrode's "Alister Mackenzie's inspired use of ground contours" because I'm a sucker for anything about the Doc and Todd highlights some good cases from his playing days.
Dr. Martin Hawtree's "The rhythm of layout at Lahinch" because I totally agree with him. Much like a good album is always better to me than just a single. A series or sequence of holes is always more interesting to me.
Jeremy Glenn's "An overview of the reverse Old course, St. Andrews" was an eye opener for me. I've got to try that somehow.
Neil's "Mackenzie's thirteen point prescription and its relevance today" was a good reminder of why the 13 have held up for the most part to the test of time.
Finally, how can we even forget Ran's article...