I'm not sure I'm a typical 31 year old but my 10p worth on what would make me go to a club and what would not...(assuming it is a concert type club or guest night)

1) quality performers who can play/sing well and can also interact with an audience
2)... who play the type of stuff I like. I'm being honest here - I'm unlikely to pay to go and see somebody I haven't heard of unless they come with a personal recommendation from somebody I know and trust who thinks I'll love it. I know that makes me unadventurous but my nights off are precious to me as are my pennies. I don't think I'm alone in this. I'm far more likely to go and see somebody I've not heard of at a festival where I've already got a ticket and can dip in & out….
3) slick organisation – starts when it says it will, finishes when it says it will, clear signage outside the building and inside so I know I'm in the right place.
4) self indulgence is probably going to put me off, whether that is residents and floor singers who overrun or organisers who book their mates even if they're not very good.
5) feeling personally welcomed makes a big difference. I play and sing myself, but am quite shy about it. If there are floor singers but I don't get asked whether I play or sing then it makes me feel left out. I know not everybody can get the chance because of time and that you can't expect, as a new face, to be asked to play by an organiser who already has a list as long as your arm of people who they know would like to do a floor spot, but if nobody ever asks whether I play then I'm not going to get the chance at all, am I? Unless I force myself to be brave enough to ask, which is a fairly big deal to a shy person.


as an aside - I have lots of friends in their 20s and 30s who are into folk music, will go to festivals, buy CDs, go to sessions and join in, but won't go to local folk clubs. I think their perception is that they're all run by people they don't have anything in common with, and that in order to see the main act you'd have to sit through a large amount of poor quality and very samey 'beardy retired men with guitars'. I'm not saying that is always the case or that having a beard or being retired is a bad thing, just that plenty of people like to hang out with people they see as similar to themselves, and its a catch 22 - (some) clubs are worried about falling numbers and failure to attract a younger audience but they can't precisely because they don't have one.
...er... not sure I can think of a solution though...