dingo,
As a guy that has flown nonstop int'l 10 years and now mainly domestic for 7 yrs (give me int'l please!) I agree with you. Never agree with slapping a child across the face. If the age is 4 or older, a little discipline said under a low voice is appropriate, then a little walk to the restroom for a more firm discussion is reasonable. But this assumes parents that care, that are consistent and kids with no serious behavioural problems. Under 4 yrs old, that's pretty much up to the kid and I've seen great parents with a small child under stress have a tough time. I always go out of my way to stop working, talk to the parents, make faces etc and talk to the child. 80% of the time it works.

Our son traveled from Europe to N America and N America to Asia several times before the age of two. Thankfully he is the perfect traveler, never once crying, even as a baby. We were very lucky, and I understand that!

As for adults slamming their seat back into my knees - three words: knees, kidney, pain.
Inconsiderate people that slam their seats back deserve a nice knee to the kidney and I never let an opportunity pass. Moving back slowly until I am trapped and in pain is the airline's fault - slamming back to smash my patella is a sign of absolute disregard for anyone else's space or feelings. Hence my stoneman's response. They are lucky it is not a club across their skull!