I participated in the Y.E.S. program in summer of 2002 with my senior class at Epcot.
It was fun, and I think it was on Leadership. We spent the first half of the day with the facilitator/leader and went into an empty room in Innoventions East? (the building with Character Spot, back behind the Coke store)
I don't remember a lot of what we learned, but they did take us over in WS and we took a large group picture by Italy with SE in the background. We all later got a nice size (8x10?) of this pic with the Y.E.S. logo and border around it.
The rest of the day we were on our own. Fun? Sure, but I think most of us wanted to be on our own experiencing the park rather than sitting in a 'classroom' listening to a presentation on leadership. But it wasn't terrible. Just something we worked into one of our days at Epcot.
I was hoping for some cool backstage action and some behind-the-scenes experiences (although I now know that is NOT what the Y.E.S. program is for! lol)
Give it a try.