As a school teacher I know there are times and places where kids are expected to sit quietly and act respectfully, but I'd never hit a kid to get them to comply, even if it were legal (they severely tempt me though, especially teenaged boys). Kids have different needs, attention spans and tolerances at different ages, and I'm sure all you parents reading this know you can't expect the same from a toddler as you can from a teenager, but they can be trained according to their level of development. Meetings and assemblies are beyond their level, so I always thougt it good when parents brought them colouring books, toys, blankets etc. At conventions a lot of parents would set up in the corridors with their families and have their kids play quietly while they supervised and listened to the talks.
There is a way to train your kids I believe, a way which doesn't involve beating or boring the poor little things. There is benefit in being trained to sit still from a young age, and it pays off at school. You don't have to beat them into it though.