I feel like I did a good amount of research before playing each of these courses, but after playing, these were the holes that I either missed in research or was completely astounded by when I played them.
Bethpage Black - #15 - might be the most difficult hole I've ever played
Prairie Dunes - #13 - doesn't need to be long to be mighty
Pacific Dunes - #3 - Everything from the tee, to the path thru the shrubs, to the approach knowing what is behind, fantastic
Sand Hills - #16 - felt so similar to several par 3's from GB&I
Ballybunion - #6 - just an awesome, delicately conceived, and nice entrance into one of the best stretches in the world
North Berwick - the entire course - I was a bit of a GB&I virgin when we played this and was left with my jaw dropped
Lahinch #6 - possibly the best on the course, but definitely not the most publicized
Royal Dornoch #3 - it is definitely mentioned plenty, but I didn't realize just how great of a vista it was, IMHO, it is a better hole than it gets credit for
Royal County Down #7 - again, doesn't need to be long to be mighty, so much strategy for such a short hole, I mean, really, is it that hard to hit it 135 hards where you want?
Muirfield #5 - IMHO - a world class par 5 that doesn't get much mention
I'm sure I could come up with many more, but these are the first ones that come to mind