Well, I can't really contribute in any concrete way since I obviously am very unlikely to be able to attend (though would certainly love to!). However, I will say that I think one of the things that "worked" for the SF get together was having a concrete place and date. Right now I suspect people are swamped by the sheer number of possibilities. I also think it helped that to begin with there was just a poll about whether you could possibly make it, and that got people thinking, and THEN they committed themselves.
Why not pick a specific time and place that you know would work for you, Martin, and then see how people would respond to that?
Right now it's like "we should have lunch sometime" "yes, we should"
Studies indicate that it works better to say something like, "You want to go to Ralph's steakhouse with me for lunch on Thursday?". It's not even important that you necessarily have the lunch then and there, but it opens up the lines of communication and gets people thinking in a more concrete way "No, I'm a vegetarian, let's go to Jane's salad bar instead".
Just my thoughts, but I'm really hoping it works out!