IMO the best choice is to buy the 1/2 price ticket for the child and use the car seats. The Baby B'air vest is good for when the child has to be out of the seat.
My 2 kids have received FF miles for their tickets, except on UA or DL when using the UA or DL number. Now, I just use the partner (DL/UA) number and they can't seem to tell that it is an infant fare.
The only problem with the car seats is that they have to be on the window seat.
I know there are the cost issues with the FAA or airlines requiring infants to have a seat, but a flight attendent told me: "We secure our coffee makers and luggage on the plane, but our infants are allowed fly through the air during turbulance."
My $0.02.
[This message has been edited by AzLarry (edited 08-25-2000).]