I belong to 24 Hour Fitness myself (I've been a member for 7+ years) but if I had kids, I would DEFINITELY consider the YMCA, since they seem to be the only place that's gym-oriented and also caters specifically to families.
The Y in my area (San Mateo County, CA) opened a beautiful facility a few years ago that not only has the latest equipment in their Fitness Center, outstanding classes in all the latest stuff (Boot Camp, Spinning, Pilates), wellness classes, body fat testing, etc. but also has a fitness program specially geared to kids 10 years and older - and we all know that the best way to get fit is to start young and learn to LOVE exercise.
The YMCA's national link is
http://www.ymca.net/ They have a great locator on there as well. If you have children (and even if you don't) I'd definitely give them a look.
BTW, if you want to hear about expensive gyms, one of my co-workers goes to Pacific Athletic Club - $140 a month (I'm scared to find out how much the enrollment fee is). It is a beautiful club though. But...I think I'll stick to my 24 Hour Fitness membership at $24 a month - not to mention the fact that it's a mere 2 blocks from my house! Take care.