For me personally I like to see:

1) The workshop stuff mentioned by Eric B is REAL GOOD stuff for me and probably many others. But some advanced players might think, hmmm I know that already. MAybe those guys can have a chat in the back -so some excellent munchies have got to be present.

2) 3 minutes solo arranger performance from each attendee would be nice. A referee must time the performance so that we can get through the people. For fun, we can have a prize for the performer that sounds the best. More munchies at the table while listening ...

3) Jam session 1 from the "featured" performers. Free Jam session 2 from everyone who can get their hands on an instrument-this might get chaotic, so if a referee thinks so, can be shortened. More munchies at the table...

4) Keyboard tryouts provided we can bring them: Tyros, KorgPA1x, Ketron, Roland, etc

5) For munchies: well, I think a potluck thing will be easiest. Voluntary thing.... if people do not bring food, well then we starve..... or get pizza or something.

I will post more as it comes to mind.