You definitely do not need bags. They sell them so your things won't get dirty/banged up. We have gate checked a stroller and/or car seat with our 23-month-old for more than 25 flights and we haven't had any major issues. Our car seat has gotten a little dirty (and wet in the rain). If there are empty seats in the plane, you could even bring your car seat on the plane and use it if you'd like. (check the airlines website for their rules, but we have done it several times on various airlines with an infant car seat).
Something to consider - we love our CARES harness, which is the only non-car seat FAA approved device. (It is my impression that airlines won't let kids under 2 sit in their own seat without an approved device but it really depends on the crew members most of the time). It is very compact so I love being able to throw it in my carry-on and if there happens to be an empty seat, we get to use it without lugging around a car seat.
Also, if you are considering bringing the car seat or CARES harness, it never hurts to mention it to the gate agent. Many have been willing to help out and put standby passengers in seats other than the one next to me to give me the best shot at having an empty seat. I didn't expect this at all when I started flying with our daughter but was pleasantly surprised! Good luck and have fun!
1. Totally agree you don't need a bag, they are just a sales pitch. Do read up on how airlines commonly damage seats to the point where they are not safe for use, yet there are obvious/visible signs of damage to make a claim. For this reason, I don't check car seats.
2. Also agree about trying to use the seat on the aircraft as a great alternative to checking the seat. However, there are no Canadian or US laws governing car seat or CARES restraint use inboard an aircraft. The rules just say you can use one, nothing about if one must be used. There are many car seat techs (myself included) advocating for this, but it is not enforceable at this point. This being said, I've seen cabin crew have their own rules, so I make sure I have saved copies of the airlines's regulations on my iPod...yes, it has come to that on one occasion, and they were very upset that I was right. The seat is installed just as you would with the seatbelt in your vehicle. I'm assuming from the age of your child that it is not an infant bucket seat, as some cannot be installed without the base and thus cannot be used on an aircraft.
3. If you are going to be flying regularly, the CARES harness can be a good alternative on board the aircraft. You should know that there are many reports of children "submarining" or slouching down and getting their throat caught on the chest clip. This is due to the fact it is a 4 point versus a 5 point restraint. Other people have great experiences...but they are not perfect.
4. If you plan on travelling regularly, some people solve the car seat issue by purchasing an inexpensive seat just for travelling, so if it is damaged it isn't a big deal. The Cosco Scenera is most commonly recommended for this purpose, mainly due to cost. That would be another option for you to consider.
Good luck with your decision and have a great trip
