I was just running through what I consider the toughest pin positions on my home course, and then it occurred to me that I was mostly evaluating them based on the places that leave the hardest putts, rather than the least accessible. Where I was thinking about accessibility it was because the location I had in mind was near a fallaway slope where an approach that goes to the wrong side (or a first putt that does the same) will fall 20 feet if it goes 1" too far in the wrong direction, even if it is barely turning. The greens have a lot of slope, mostly back to front, but the locations I had in mind also have a lot of sideslope as well and are about the max slope locations that are pinnable (offering a hell of a lot more break on 4 footers than the pin locations they use on tour)
Given the ability of today's top golfers in terms of distance control and spin control, combined with the distance the of the modern driver and ball making 450 yard par 4s a wedge approach, is the idea of choosing locations based on their accessibility in terms of approach angle or being cut close behind a bunker really appropriate if you are trying to test these guys? I think it'd be best to find the places that'll give the most difficult putts. They are going to successfully shoot at the pins no matter where you put them most of the time, but if its in a place with a lot of slope that's going to give them a lot of fits.
Just look at Tiger at Oakmont and Carnoustie. When the 5 footers have a bit of break to them he misses them once in a while. Give him a typical PGA tour course where he can hit those hard enough to not give away the hole, he never misses them. The other guys are a bit more human in their ability to miss straight putts, but its still easier for them than when they have to combine line and speed together instead of just ignoring line because the pins are cut in a flat spot all the time.