Fun reading and great thread idea. I could go on a lot on this topic and I equate unusual with good.
Trying to be concise...
-Sentimentally, Stembogen at Blue Knob, PA has a little bit of everything including sharp banked turns with multiple fall lines, flat-ish switchbacks between turns, skiable gladed terrain off the side of the trail that can be sampled when natural snow is good, has a bowl-like section at the start and a wide-open powder field at finish.
Scenes on or overlooking Stembogen Trail:
-Last year I skied Muleskinner at Saddleback, ME for first time, fun, narrow, twisty, extraodinarily scenic trail. Cameras on fritz, but here is a link I found to an old trip report on Firsttracks with some pics (doesn't show great lake views): http://www.firsttracksonline.com/boards/viewtopic.php?t=703&highlight=saddleback
-Not probably unusual for the west, but I thought the gnarly trees and beautiful rocks of Catherine's area at Alta are very special. This is either So Long or Last Chance trail:
-For a little hill (~1100' vert) Black Mtn, NH has some unusual terrain including very challenging glades, little cliff drops, much of it ungroomed. This is below a natural feature called Hanger Cliff:
Lower FIS at Sugerbush is similar to Lower Antelope at MRG, long, lonely single black bump runs that convey a feeling of isolation/exploration even though lift served.
As mentioned by others, the network of beautiful glades at MRG is unusual in a very GOOD way. Paradise Glade:
Aforementioned Honeycomb Canyon at Solitude, UT, is a big area of lift served side-country that is real pretty:
The entire atmosphere around Le Massif in Quebec, Canada is very unusual for its setting next to the St Lawrence Seaway, which is practically like an ocean there.
Lunch is over, much call it quits now.