Thanks to all who responded. We have decided that our jams have gotten to big. They would be sing-alongs, but not enough people sing along. We're changing our format to "open mic" first and then allowing people to hang around to jam, but not try to organize this. This has happened naturally and the hottest "picking" of the night usually involves these smaller (3-8 people) informal jams. After the "open mic" people seem more relaxed too.

One tip I'd pass along that I picked up at a bluegrass jam is that whoever is leading the song lifts their foot to signify the last verse or chorus of a tune. That way everybody ends clser together.

Acoustically,

Steve