You may want to add something about mountain biking in the summer. I have been there a few times to both bike and hike. In the summer the chairlift runs and is used to transport people and bikes to the top so they can bike down. Also from what I have seen it does get fairly crowded in the summer just because of the touristy nature of Waterville Valley.
"After the first glass, you see things as you wish they were. After the second, you see things as they are not. Finally, you see things as they really are, which is the most horrible thing in the world."
--Oscar Wilde on Absinthe