Most parties in the Hamptons are very detailed, themed and scripted. Spontaneous things like the host jumping on stage to jam with the party band and the guests joining in to sing and play just for fun is very against the "norm" of party giving.
A college buddy of mine is a chef in Conn. and moonlights sometimes with a caterer that does alot of Hamptons parties. he sends me menus and instruction sheets , they have things like the exact minute a certain course should arrive at table, exact lists of who gets served in what order, precise times when the entertainment should be seen/heard and not. it's crazy.

Sounds like a blast of a party, would have been a cool night to be a fly on the wall. I wonder who decided it was time to kiss and make up Jann or Jon??