Just saw this thread and thought I would chime in...
I'm part of the Detroit Pinball League which has been running about 10 years. We meet (almost always) at people home collections. About 20 to 25 members. The league has gone through some ups and downs but has persevered. It has a formal structure with a president, secretary, and rules committee. A lot of the rules are to protect the hosts. The structure can be a hassle but IMO also allows it to carry on.
It is great to play and have fun but the best part is seeing and experiencing other members home game rooms. These vary from 5 games crammed into an unfinished basement to 30+ games in incredible home game rooms. The league requirement is 5 or more good working games. With about 6 monthly meeting per year people only have to host about once every 3 years. Many host more often though.
I live out in Chelsea now (about 10 mins from AA) and know of 4 or 5 AA area collectors that could host. I am sure that there are more. If people are serious about starting an AA league I could get a copy of the bylaws and rules of the Detroit league for an example.