I actually did a coffee shop karaoke show for quite some time at the Mighty Cup in Glendale, from 7-11pm on Tuesdays. Attendance was really good after a while, with a mix of Sober Riders (bikers who don't drink) and youth AA groups. The problem was that although the place packed out for it, without alcohol sales, it never made the place enough money (and often lost money) and eventually the owner had to let me go. Cups of coffee just don't generate the cash beer and booze do.
-- Dan Dan