I can't thank you guys enough for all of your responses. There's a ton of information here. I'm a bit overwhelmed at all of the choices! And here I had been under the impression that the folk club, as an institution, was "dying"...

To those who asked, I'm approaching the project as an anthropologist, not as a musicologist. My concern is with how folk music is given meaning and used socially. So my emphasis will be more on talking to people than strictly listening to music (though, of course, I also want to listen to the music). The ideal club(s) would be somewhere where the regulars would be willing to talk to an American interloper about folk music.

It sounds much more plausible than I had originally thought. I'm still worried about transportation, as I'll basically only have my feet and the train (and taxis, if necessary). I guess I'll have to position my location perfectly to make things work out.