Back in 2001, when I started going to these things, the attendees were mostly college age and older, now, it seems the average con-goer is about 16 or so, with many in the 13-14 range. That’s mostly due to the shows being on TV and widely available on DVD, when I first got into the fandom, only specialty stores like Suncoast carried Anime, and it was very expensive.

I’ve not been to A-kon, as I’m in the midwest, but most anime cons are similar, they only vary in size really. I’m glad you made it into a family event though, I’m not sure what age your daughter is, but I do know many parents dump their pre and young teens at these things for the weekend and have no idea who they’re staying with, and while illegal activity is usually pretty low at all anime conventions, there’s always some creepy and questionable people at these things, I usually stay with my 15 year old niece at conventions, or have her check in every couple hours at least.

I mostly spend time with people in my age range at these events, and while the majority of attendees are high school kids, there’s usually a good amount (probably at least 25%) of over 25 adults around too, and mostly ones who are there for themselves, not with children. It’s an odd little hobby, but like you said, the people are mostly nice, and most everyone there are hard-working, fairly normal people who just choose to spend their spare time and money at a rather strange and dorky event.

Oh, and the shock never wears off really, not even when you make and wear costumes at them yourselves, I still see things that are bizarre and freak me out.