Update: This thread inspired me to seek out and play more extreme disc golf courses. I really enjoy a challenge and I don't have a fear of heights. Over the past year I have played the following "extreme" courses that are NOT at a Ski Resort... I have listed from toughest to not the toughest.
I am going to have to give the nod to Bucksnort DGC in Colorado AND Diamond X in Montana.
Top Two:
Bucksnort DGC - Pine, CO
Diamond X DGC - Billings, MT
Tied for Third:
Goblin Valley State Park DGC - Green River, UT
Makoshika State Park DGC - Glendive, MT
Ironside DGC - Cedar City, UT
Only 9 hole course to make the list:
The Boneyard - Globe, AZ
Finally:
Sugaree - Newland, NC
Sugaree is the only non-western course on the list. To be clear, Sugaree is extreme for an Appalachian course, but not so extreme when compared to these rugged, Western disc golf courses. Western courses are very exposed to the sun, weather and wind, while Sugaree plays among the beautiful shady Appalachian woods.
Most extreme Ski Resort courses I have played:
Las Vegas Ski and Snowboard DGC
Brian Head Resort DGC
China Peak Resort DGC
All of these ski resort courses have a lift ride UP to the first tee. So, while they have extreme elevation changes and some extreme "black diamond" terrain, you get an easy ride up. All the other extreme courses I listed require YOU to walk up and down to play - no rides!