I was recently at a Hacker Festival in the Netherlands, and one of the things that I found neat was that there were plenty of kids there. There were activities on the timetable for kids, as well as spaces that were dedicatedly for kids. However, the event didn't feel like it was at all diluted for the sake of families — areas and activities intended more for adults still existed, as well as a general expectation for adults to be responsible and courteous when engaging in adult-only activities (such as drinking alcohol).
It felt like a cool model of coexistence that we don't get exposed to as much as we should in The Real World (TM). Whilst this openness towards the kids is partly for the parents, it's also cool for the kids who want to take part. For example, I remember that during a soldering workshop, I got talking to a boy sitting at my table — I think he was age 10-12ish. Whilst there was some level of me having to be mindful to be speaking with him in an appropriate way, this didn't prevent me from engaging with him as a peer; we had an earnest conversation about projects, and the usefulness of concrete goals; hobby burnout; and how much ambition is useful when you're learning a new skill. I wish I had more opportunities to hang out with kids in a capacity where I'm not actively in a mentoring role