I am sorry Joe but I always get the giggles when North American skiers talk about huge resorts.
Yes, I used to ski Winter Park with a friend from Paris. He said the snow was much better than Chamonix, but WP/MJ didn't have any vertical...
North America, in general, lacks the huge conglomerations of connected lifts and runs under different, but cooperating, management that one sees in Europe. On the other hand, I suspect a higher percentage of North Americans place a higher value in skiing off piste, since most NA ski areas do not have the glacial hazards (crevasses, etc.) that exist in at least some areas of Europe.
As JoeUT says, if you're limited to groomers, the Powder Highway definitely presents some challenges and may not be to your taste. In many of the available areas, the primary attraction is difficult off-piste terrain and very soft snow.
Sorry to hear about your bad experience in Whistler. Whistler/Blackcomb has a large selection of groomers when the weather is more cooperative.
I don't know you or what your issues with your knees are, but it should be noted that subtle refinements in technique (stance, in particular) can often make life easier for old knees and may open up additional terrain for you. With many days, and years, of your existing well-established technique, it can be difficult to make changes, though.