Your best bet other than Boulder would probably be Mount Snow. Otherwise Killington or Okemo is never a dissapointment both of their websites tell you exactly what they have set up on their main parks. If you feel like going a couple hours further than Stowe.
Stratton also just held the U.S. Open. I went to it in the very early 2000's and if I remember right they left the competition setups up for the public afterwards.
I barely ride park up north though, there so much more natural fun to be had in the trees that we can't have here in PA.