I haven't used either of those options. But having flown with my son a few times since he was 16 months, it is just as easy, if not easier to just carry the carseat alone. With flights being as crowded as they are these days, and the airlines not really giving you much time to get in your seat, the less you have to handle, the better. Strapping the car seat into the airplane seat isn't quite so easy either when you are trying to get it in quickly so you and the rest of your family are not blocking the aisle. If you are flying an airline like Midwest, where there is more room, it's easier. But someone like Southwest, it can get a bit cramped. Make sure you check in early so you can get a pass to "preboard". Hopefully they give you enough time to get settled before the rest of the passengers start coming on.