Nowhere near your location, but I am the President of the Vancouver BC Mac user group and can tell you from personal experience that we have an impossible time getting younger people out.
We offer all kinds of presentation topics and free gifts and discounted subscription costs but younger people just don't seem interested.
You can blame things like Google for it, but people just don't get much out of user groups nowadays. Sure, I get around 40 - 50 people each month, but they're always the same ones. No fresh blood, no new ideas, no volunteers for presentation topics. They just want to come out and talk with their friends and drink coffee.
]You can probably sense my frustration, but I'm not really frustrated with the people, because I feel that user groups have had their day in the spotlight. It's just too easy to communicate via the likes of Mac Rumors and IM. And we can all answer our own questions online.
Good luck with you group, I hope you have a lot more success than mine is having right now. I'd love to see a rebirth in user groups.
Apple doesn't help much either. I used to be a member of a Windows .Net programming group, and to their credit, Microsoft really seems to care about user groups. They'd sponsor the whole evening once a month. Paying for the room, supplying pizza and refreshments, supplying presenters and all kinds of freebies. And it's really hard to get Apple to come out and when they do we get a sales presentation. It's still interesting but that's all you get.
Anyway, good luck.
Cheers.