Children are rather like dogs - that goes for their behaviours and most other things!
They can smell fear - so if you're worried - they'll magnify it!
If you're confident and competent - they will act like they usually do. So if you're kids are ill mannered little toerags - strangley enough that's what they'll be.
My daughter flew with me from a couple of months until she was 13 (flying is now no longer cool - largely because her friends cann't do it and so it's too elitist.
But up until she was 4 or so she generally slept. From about 6 she wanted to fly and by 11 she was an expert at cloud busting.
I remember it as a series of wonderful experiences.
She always had hearing protection, initially just ear defenders then a kid's headset. In the back she always had a car seat and generally enjoyed it. In the front she had a booster seat (and I worked the pedals!).
So if you don't know the kids get someone who does. It they haven't flown (the minder that is) before they are a no no - they also must exude a level of confidence - remember kids can smell fear and many of them can be very wimpy!!
This is not a huge adventure - it is an everyday occurence, its supposed to be boring - if it isn't then the 'pilot' is n't doing his job. Then the kids can look out the window and enjoy things and that is the point.