Patrick:
I recently have thought that spines or ridgelines are probably the single feature that shows up most holes that I find particularly interesting. To me it is an ideal feature because it provides significant reward without undue punishment. A less favorable angle, a sidehill lie and a blind shot are all factors that one will work hard to avoid, but recovery is possible and the punishment on a poorer player is relatively light. Most of the examples I know well would be unfamiliar to most, but here are a few:
16th hole at Waveland GC - Des Moines, IA. A 465 yard par four with a high spot on the right side of a ridge that starts about 150 yards off the tee on the right side of the fairway and ends around 250 yards off the tee on the left side of the fairway. Because of the length of the hole and a prevailing headwind, you want to be as aggressive as possible, but need to get to the top of that ridge.
5th, 8th, 13th, 14th, 18th fairways and many of the greens at Oak Ridge Country Club, some of which I am trying to hilight in my My Home Course profile which is still being finalized.
Here is the 435 yard 18th looking backwards at a little valley that provides the interesting feature of the hole. If the valley can be skirted by hugging the right side of the fairway (left on the picture), one gains 40-50 yards, a visible shot and a flat lie:
Some better known examples:
The tee shot on that par five on the back nine at Sand Hills where a drive close to the bunker on the left gives rise to the possibility of mortals reaching a 600 yard hole in 2.
The tee shot on 9 at Lahinch. A great tee shot can get past the ridge. Otherwise, one is better off playing for position on the blind second.