Never, ever, ever rent a car seat. You don't know the history of the seat and it could have unseen damage that could cause it to fail in a crash. Also, it is not uncommon for them to be filthy, expired, assembled incorrectly, missing parts, or the wrong type of seat for the child (i.e. an infant seat for a 3 year old). Take your seat or pick up a cheap Cosco Scenera for traveling. If you can get a seat on the plane for your daughter, I highly recommend it for safety reasons. If not, take your seat to the gate and see if there are empty seats on the plane and if you can use it. Worst case scenario, they won't let you use it an you gate check it. Don't check it with your luggage. I have personally witnessed a car seat fall off the luggage cart, get run over by the cart, the guy stopped, tossed it back in with the luggage, and drove off.