I am considering starting a session of sorts here in Georgia. We have few opportunities to jam with others and when something is available it is normally one style, mostly bluegrass.

I have a venue that would be glad to host us and would even give us a lot of publicity, and I have decided to start the first session with a set by my folk group, The Brookwoods, and hopefully I will be able to attract a fine group of Celtic musicians that is excellent but have few performance opportunities locally.

What I thought I would do is have each group do a 20-30 minute set then open up for a jam session or open mike for the rest of the evening. My questions are:
1) do you think we can successfully run an eclectic session with some folk, bluegrass, celtic and even singer-songwriter, jazz and oldtime folks thrown in for good measure?
2)How much structure do I need to give this to maintain some control over the music quality etc so the owner of the venue gets what he wants, attracting business to his winebar?
I guess just some general info on sessions, open mikes etc would be helpful as I have almost no experience in this area at all