You have to decide up front what you want, and they are diametrically opposed, I think.

Do you want a community experience that involves sharing and supporting? It includes music but the community experience is the important thing. Go to Plan A.

Do you want the best possible music, and is that in place already? If it is not, I don't really know how you will get it, but assuming it is in place and you want to keep it that way, go to Plan B.

Plan A.
Take turns. Religiously. Have a great big circle, the bigger the better and keep moving the chairs back and back. Allow if not encourage the blue books. Don't worry if they are not to GB yet. They are on their way. In fact, paperless options are now on their way. Get your computerized projector out. Turn the flourescent lights on as bright as your eyes can stand so that people can read their music.

Plan B. If you already have great singers, do what they do. Ask them what they like and what will make them show up and not show up. If they like Plan A, you are home free. Chances are they won't but they won't tell you but then they won't show up either.

Default is Plan A. It can be very enjoyable for all who come. The others will be somewhere else, and if I knew where I would join them and just listen and not care if I personally got a turn or not.

There is no right or wrong. I am more about preserving great music conclaves rather than setting them up afresh. If it is great don't mess with it. mg