There's a place in the Chicago Suburbs called the Acorn Coffee Bar in Warrenville, that does workshops and sometimes can book concerts on short notice. The Lake County Folk Club, north of Chicago might be a place to look as well. I suspect that google can turn up links to them. If it weren't so close to the Fox Valley Folk Festival, they would probably be interested as well. I've been thinking furiously the last couple days and can also think of some individuals that might want to try setting up an informal workshop or house concert, but think that might not get as many people as you'd need to justify setting it up. Like I mentioned, above, a lot of places shut down in the summer around here.