I suggest doing vail for 3 and BC for 2. Believe me, Vail is huge, and even in 3 days there is no way you are going to be able to thoroughly cover all the terrain that they have to offer. My suggestion take the gold peak quad up all the way, get off an take chair 11 to the summit. Then take the cat walk off to the left all the way to blue sky and hit that shit up for a while. Check out steep and deep, and lovers leap for the more gnarly shit, or check out the runs on the otherside of bluesky(on the right if you are on the lift) for some sick glades. If you get bored in bluesky, check out some of the other bowls. Some of my other favorties are highline and blueox for length and steepness, and chair 4 can be a fun one to lap. Check out the cliffs under chair 4 and bust em huge if you wanna be like me (haha). Have fun at Vail dude, it truly is immensely huge and unlike many other resorts.