I think there are two good categories for OH WOW! second shots.
1) Where the visual is the key even if the golfer has no clue about the architecture.
2) Where the knowledgeable golf architect aficionado appreciates the shot to be played (although there visual may still be stunning, as well.
Category #1: #8 @ Pebble, #8 @ Fishers and #'s 9 & 10 @ Pebble have already been mentioned. Obviously, the presence of the ocean adds a lot to the visual impact of OH WOW! I would add several holes at Casa de Campo and #13 at ANGC to that list. Also, #8 @ Dornoch and #9 @ Maidstone deserve inclusion. The Golf House Club at Elie has at least one approach shot that, like #8 @ Fishers, has the ocean as the background.
Category #2: The OH WOW! is in the appreciation for shot that must be played irrespective of the view. There are hundreds of candidates for that and my nominees include: #'s 8, 13, and 15 at PVGC, #'s 5 and 18 at Merion, #'s 3 and 8 at NGLA, #'s 8-10 at Pebble, the short uphill par 4 at Cypress (#8?), #'s 9,10 and 13 at Shinnecock, #'s 9 and 10 at Maidstone, #18 at TOC if there's a big crowd around the green, #10 at Riviera, #'s 3, 5, 10, 11, 13 and 15 at ANGC, several at Seminole (not just #6), #18 at TPC Sawgrass, #14 (Foxy) at Dornoch............the list is long and gets longer every year, it seems