I'll go Monday. I'm not a huge fan of Hop Haus, but it is very easy to get people together there; on a Monday night, the dining room will be pretty much empty.
(We do ChiSec every month at Hop Haus).
Hopleaf is D.O.A. for a meetup. It's a madhouse every single night of the week.
I'd love to convince you all to meet at Violet Hour, but I'm thinking $11 cocktails don't match the Chicago startup ethos.
Well, figure out a date and let us know here; I'm not sure why Google Groups is a better place to organize a meetup than right here, though.
My advice, after doing ~30 ChiSec meetups averaging ~30 people in the last year and a half, is just to pick something, get people together in a room, and then if the date isn't perfect you can move it next meetup.
Agree about the google groups thing. Someone should just register a twitter account for HNchi or YCchi like the Melbourne guys did: http://twitter.com/ycmelb