I find socialisation with different age groups is highly beneficial for children. I went to a lot of parties as a child that a lot of people would consider "Adult". Drinking, joking, merry-making, swearing. Children everywhere, of course, but we made our own fun and the adults were unimpeded in their adult pleasures.

Kids are both highly adaptable and very open to new activities, which makes keeping them occupied at cons not quite as hard as people would imagine.