Hi Muppet,
Best of Luck with your event.
May I make this small comment - I think it would be an idea to allocate one of the venues to be concentrating on just Musician Sessions.
It just saves musicians carting their gear from one venue to another looking for a sesh and where perhaps only one or two musicians are in each venue - waiting or looking for each other. A Focal point if you like.
Then they also know which venue to park near.
What d'ya think ?.
It was just an idea.
Success
Betsy