In the early '70s, "The Focus" in Manhattan was run by Debby McClatchy who booked it and baked for it. 'Twas a grand place to hear great music.
Before that, it was Gerde's which was a bar and not a coffee house. They had the best open mike in the world. All the New York crowd and a lot of visiting singers showed up there on Monday nights. It was hosted by Brother John Sellers.
Another bar that had a great open mike was "The Red Fox" in Silver Spring, Maryland outside of Washington, DC. This one was hosted first by Mike Holmes and then by Bruce Hutton of the Double Decker String Band.