The Air NZ demo is fantastic - and from my personal experience, it actually got people watching.
When I was a single digit, a QF flightie with some time on her hands on a long haul flight pulled out her demo kit and for about 10 minutes allowed my sister and I to play with the shiny yellow equipment (still have the photos!).
It stuck with me, and as an 'grown up/flightie' I always took the time to 'entertain' the unaccompanied minors and restless children with the demo kit. Apart from the fact they think its a blast, the learning opportunity to touch an oxygen mask, or dress up in a yellow life jacket could just save a life. (Sometimes we used to play a game, awarding the fastest two children to put on a life jacket with a bag of lollies, before making them 'honorary flighties' for the day, getting them to hand out lollies or deliver a few drinks).
It was a winner 'every' time - even the crusty old businessmen would crack a smile.
If you can get away with it - do it - the parents will love you for it, and you might just save a life. At the least, you'll make the excitement of flying all the more memorable for your young passengers.