I think the suggestions about South America and NZ may win this contest. Haven't been to NZ, but have heard access roads to ski areas are exciting, basically because you are rising great verticals from semi-tropical to alpine environment. Treble Cone access road talk: http://www.wanaka-alpine-holidays.co...ki-resort.html
No comparison to NZ , S. America, or Alps, but in US some of the more interesting access roads I've been on include those from Boulder to Eldora and from Santa Fe to Ski Santa Fe. Middle-of-the-night drive up from the direction of Sacramento to Kirkwood, CA for my one and only visit there was no piece of cake either. Honestly, anywhere in big western mtns during a storm can be exciting for us flatlanders.
Like Telerod15, however, my personal most harrowing ski trip driving experiences have occurred on the access road to little old Blue Knob, PA where I've had a couple sliding-backwards-out-of-controls incidents over the years, one down by the State Park swimming pool, the other on final climb before the summit parking lot. Blue Knob is one of those upside down areas where lodge and parking is at summit of ski hill and due to latitude, elev (3000'), and local weather might be one of the most challenging ski area access roads in the East with that type of configuration.