One of the better festivals I've been to was the Oberhausen Short Film fest. in Germany. I had Emily's Song in the kids section, it was great, a brilliant experience, loads of fun and I found I preferred the films... they tend to be more narrative based, rather than experimental... but that's just me... anyway! They were involved with all the schools in the area and they bused them in every morning, class loads filled the theaters, it was great. And the thing about kids, they have no problem telling you if your film sucks! Thankfully they liked ours!
Something else worth thinking about is making an educational thing of it, we were part of the Showcomotion film festival in England, where we picked up the UNICEF UK Award, and they made questionnaires based on our films for the kids and had discussion groups.
For example, with Emily's Song, they asked, what song would you have at a funeral and why? What would you do if a loved one stopped talking to you? How would you help your family if they were in trouble? and so on. I thought it was a great idea... I just wish I could have been there to hear the answers!