One thing I learned from having our first baby and flyinf soon after, is that some of the crying is caused of course by ear pain, children not knowing or being able to "pop" their ears during take-off and descent. There-for, we always tried to nurse our son during these times, as the swallowing helps to un-plug the infants ears. It has worked well, so far!

Also, be sure and tell the res agent that you have a lap child and would like to try and block the middle seat, if this is the way you go. Also, be sure to carry proof of age (immunization card, birth cert., passport) because if the airport agent doesn't believe your child is under two, and you can't prove it, you can be forced to buy a ticket.