As long as the kids are well behaved, I don't care where they are.

If they're not well behaved, well... I had a horrible experience on the UD with two "prairie dogs from hell" (as Dave Barry puts it). One a toddler, who kept stomping up and down the aisle. The other an infant, who was literally shrieking for half the flight. The mother was oblivious and remained so even after giving it a rattle which it proceeded to smash against the wall. Apparently even the pilots complained about the noise. A very, err, rare UD experience I'll put it that way.