Assuming you follow CassMT's advice and don't become a statistic, even the most terrible unfun runs like that teach your body something, especially when you go back to a green. Don't Give Up!!
Given the amount of time you get up at Whistler, I would get on the "lesson" band wagon. Not only is it bound to help your technique, who better to steer you in the right direction in terms of runs that are in your "skill spectrum" than a certified instructor who just spent an hour or two watching you board. Seems like on a mountain of that size, there should be a nice set of groomed progression runs that you could step through while practicing your techniques, getting comfortable with speed, and work on handling varying snow conditions. I dunno.
Most of my season is on Mid Atlantic mountains, but just came back from a week at Sun Valley. It was pretty big, and there was definitely something to that "color ratings are relative to other runs ON THIS MOUNTAIN" thing, because a blue at Sun Valley could be significantly more challenging that the average blue run found in MD, PA or WV. Not to mention about 3 times as long. We got a tour from a couple of locals the first day, but I still felt like I had to be careful not to end up somewhere that I couldn't get out of in one piece.