Don't think it's been mentioned yet, but here in the Kent, se London area there have been a few weekend events, which though I have not attended yet, I hear have been quite successful . These involve booking a more established artist but with plenty of time for floor/open mic spots. As noted above many of us don't go to clubs if it's a booked guest, as our interest is more in performing/participating ourselves, but the mixed format affords an audience for the paid guest, who largely will also be performing, perhaps partly in order to play to more people themselves. I suspect some may find this an undesirable arrangement, as the quality may be thought poor in some cases , but it seems to be a realistic strategy that's working....at present. Personally, I prefer variety , however good/established, a paid artist might be.