Interesting comments from folks about Breck. It's one of my favorites, together with Copper. I also think the Birds at Beaver are reasonably challenging, although I haven't skied them in some years. Vail is just plain massive. I hadn't skied there in some years, then took a clinic there last year. We covered most of the area in two days. Well, what I really mean is that we saw
most of the area in two days! Every time we'd cross a ridge, I'd think, "Surely, this must be the area boundary!" But, no, there was just more skiing beyond that.
As long as you stay away from the front side of Keystone, I think you'll likely have a great time. Especially since it's already dumping. God willing, this could be an Epic year!
The real question is what kind of area do you really like? They have very different personalities:
A is funky and old-school, Jimmy Buffet kind of place.
Keystone is family central. There's some decent skiing on the back side, and the finest on-mountain dining around.
Breck is international and mid-level. Some fun skiing off the top of the mountain, and peak 7 has the most inviting blue terrain around. The cuts through the trees make it feel like skiing in a park.
Copper is very large, too, and the bowls have some great skiing.
Vail is huge and the back bowls are the place to be on a powder day.
The Beav is beyond money. Ritz and Hyatt. And it skis like it. Think Deer Valley in Colorado.
Hope this helps...