I know we are talking about Urban Design, but I found it difficult to find "child sensitive design" in Architecture too.
My final project to school is a Children's Home, and doing research in design FOR children I found schools designed so they can pay more attention, so few were designed so they can grow as people, encouraging creativity, curiosity, willingness to learn. While researching for homes, I found houses designing for grown ups, sometimes their kids have a playroom, playground and that's it.
Going back to the urban design, I've been also struggling with this, cause I don't have where to send those kids to play outside so my current challenge is not to design only their homes, but to design a small piece of city so these kids can live this city, can experience the city they live in.
Kids usually are so sensitive, they will easily help you to find what is that they like, or if you go back in your memory, try to remember places you went to in your childhood, you can remember of colors, smells, tastes sometimes, sizes, people and you know why you did or did not like those places.. then do it!!
In Guatemala we have many children playing in the streets, but we don´t have places design for that so its dangerous. Its a shame but i´m shure that the violence we live every day, its makin that the public areas are not safety places to be. The urban designe gets defined for that problems. i hope this might change.