From Jens:

I just reserved the location ( ) for Friday, June 13th from 2pm
We have two possibilities for the room:
1) Bachhushalle (Cellar with wine casks)
can hold 40 people with tables, up to 80 persons without tables

2) Fürst von Bismarck-Saal
can hold 140 people with tables

She blocked these two rooms for us and we should give her notice in the
next 3 to 4 weeks. May be we could also get other rooms and/or combine them.

On Saturday we could take a Rhine river cruise (not part of the event but
arrangeable by interested individuals).

Any thoughts?