Just a quick thought from a former airline pilot (please excuse the interruption but I feel strongly that "lap children" are not as safe as they would be if they were restrained in a an FAA approved car seat or CARES device)
The NTSB has recently requested that the FAA make it regulatory for all passengers - regardless of age - to be seated and restrained in a separate seat during take off, landing, and during turbulence.
The FAA has stated it is safest for children to be restrained in flight but has not mandated restraint of these defenseless passengers. Instead, children under the age of 2 are allowed to sit on an adults lap endangering not only themselves but every other passenger in the airplane cabin if there is unexpected turbulence or aborted take off or a crash landing.
The forces one would encounter during the rapid deceleration of a sudden stop or impact are simply unsurvivable without proper restraint. They are mandated in cars... but not airplanes where the forces are exponentially higher?
If you don't like carseats (they are pretty cramped in RJs) then do a search for the CARES device (good for 22 to 44 pounds). They even rent them on eBay. Best thing since sliced bread for traveling via airplane with your little ones.
I was an airline pilot for many years (and still fly professionally). I would strongly advise against "lap children". It is extraordinarily unsafe and no savings of a few hundred dollars is worth the risk.
Ok, off my soapbox. Here's the link:
http://www.ntsb.gov/safety/children.html