Hi John.
I've done a couple, once at my son's kindergarten, and once at his Scout group.
The kindergartens were too young, the scouts were just about right, so anywhere from 6+ yrs old is the right audience.
I planned it around having a moon and a planet in the sky at the time, so a first quarter moon is ideal, and with Jupiter overhead from dusk you can't go wrong there.
I wouldn't try showing any faint stuff, some bright DSO's would be ok, like some nice star clusters (jewelbox, omega centauri, etc).
Kids also love to hear about the scale of things, how far to the sun, the (other) nearest star, etc. and relate it to things like driving, bus to school etc.
Supervision is probably required, at least, you'll need them to form an orderly line, explain to them where to look, where not to touch, what they should see. You might need a step ladder or crate for them to stand on too.
You'll also need to be prepared to jump in between each kid to make sure the object is still in the FOV. Nothing worse than a kid saying "ah yeah, that's excellent", and then you go and have a look, and find it wasn't in the FOV at all
I found that the parents (of the scout group) loved it moreso than the kids! I'm planning to go back there again soon.
Good luck!