I like to say that we are kid-friendly but not exclusively for kids. I have a young son and I look forward to working on projects with him at the space, but I also look forward to working on my own projects and especially look forward to working on projects with my ladies tech group.
We have had classes that just aren't great for young kids..like our zombie makeup effects class...but we balance that with face painting so it feels inclusive.
We differentiate ourselves from most hackerspaces because we want kids around. Didn't a 15 year old just make a major break-through in cancer research? In order to do that we are creating a section for young kids to hangout when their parents are soldering, etc. and we require kids under 13 to bring a parent or guardian with them during open project times and many of our classes.
The key is that you are comfortable with kids around and understand that it may get noisy!