We've gone the past 3 years in both May and October. They advertise the "Backyard Neighbors" special on the radio, but I've never seen it "published" anywhere else. The price has gone up from $99 (in 2009) to $129 (in 2010) for a family of 4. An additional person /child is $40. Last year, they extended it through the middle of June, so we went the same day as the Pocono 500 (NASCAR). When I realized it was the same day as NASCAR, I thought we'd totally regret it because there's essentially one way into Pocono Raceway and one way out... passing GWL... but, in fact, it was a ghost town that day. None of the locals want to leave their houses with all the traffic and all the race fans were already at the track by the time we checked in.
They have no announced a "Backyard Neighbor" special for this spring yet, but I have my ears peeled ...
Also, I passed along the code to a friend who lives in NJ last time around and the code wouldn't work for her because the credit card she attempted to book the room with had a NJ billing address. I guess you have to have a PA billing address.