I went with my 14 month old daughter last year. She was free, but had to sit on my lap during the flight (no car seat was needed). If your daughter is older than 2 she will probably have her own seat, however, if she does not, I would get to the airport as early as possible to reserve the bulk head seating on the plane (i.e. so you have additional leg room during the flight). Additionally, I would bring the portable DVD player, a few of her favourite toys and some snacks to eat on the plane.