Sitting at different places is a great idea.
One idea would be to assign an "ambassador" to each new member. Sombody who is outgoing and active. Match up types of quilters. Then the ambassador could help the new member through the first year, making introductions, explaining procedures, encouraging the new member.
In other organizations I am in, as a member, you have to pay a minimal fine ($.25) if you DONT introduce yourself to the guest during the social times before and at the break before the presenter. This works in smaller groups of 20-25 people, maybe not 80.