Oh yeah, constellations and milky way, duh! I forgot those!!! I had the pleasure about Six weeks ago of having a few kids at the scope. It was completely unintended, it was a young boy, his best mate, and the boy's father. They were visiting their sister who lived at our next door neighbours. I had a mate over and we were just starting viewing. We had a crack at Jupiter, Saturn, moon, 47 Tucanae, no Omega unfortunately as a tree was in the way, thus blocking the view), m57, alpha centauri. We spent an hour and a half, and we all had a blast, including the dad. It was great to have some young kids showing interest, they were really excited by it all. m57 was the least popular item, since it was faint and tiny. The moon and Jupiter were both the most popular items, followed closely by Saturn. If I was to add a bit to this, I'd say M8 would be one other item I'd consider, since some nebulosity is visible. Dark skies and a UHC filter would make it even better I suspect.
Don't neglect the parents - if you hook the parents, they're more likely to be inclined to come back for a return visit (and bring the kids) imho. If parents get bored, they won't bring the kids back, since it'll mean more boredom. That's my logic. Remember, parents dictate what kids generally think. If mum & dad likes something, odds are, the kids will as well. Monkey see, monkey do.
I don't think it's good to get over technical with them, the old k.i.s.s principle is always best when dealing with kids. Let them ask questions, encourage them to. Even the kids who ask silly questions should get a pat on the back - it's better to ask a question, even a silly one, than be silent.
Dave