The answers so far seem to define challenging as "greatest risk if you mess
up".
That's a fair definition but if you go by difficulty of execution then the
NDB
to Siskiyou County, CA, (SIY iirc) looks like fun. I've never flown it but
it involves
a substantial dogleg at the NDB (particularly good if there's a crosswind)
as well as a death-defying descent rate on final.

John

"Angus Davis" wrote in message
...
I am curious to hear this group's thoughts on the most challenging
instrument approaches in the Western US. Perhaps this not the best way
to phrase the question, because I am planning a trip with a fellow
instrument student and our instructor around the Western US this winter,
similar to those organized by outfits such as IFR West. So, I am
looking for challenging approaches that will be a good learning
opportunity for the instrument student. I fly in the Bay Area, so I'm
no stranger to ATC. We will probably do the trip in an all-glass SR-20,
so no ADF. I consider "Western US" to be anything where radio stations
begin with a "K" Thanks in advance for your suggestions,
-angus