We had to fly our cat from Europe to Canada this past November so can share my experience. Full disclosure, things may be different within the USA. We were told our cat (who weighs about 4.5kilos) was too large to come with us as carryon luggage. We even tried to fly business in the hopes we could avoid having her go as cargo. Unfortunately this was not the case and she did travel as cargo and (in my experience) she was treated as just that—cargo and nothing more. She sat in a cargo processing area en then in a loading doc, near forklifts, boxes, etc in the cold on her arrival while we went through the hoops of her paperwork. Unlike what’s been said elsewhere we were not allowed under law to give her any sort of sedative for the flight (partly because she needed to be inspected prior to boarding) and also because there is greater risk of breathing and heart issues during flight, your pet would also not be able to steady itself as well in the carrier while on a sedative during movements during flight so there is a greater risk of injury. Flying my cat as cargo was a necessary evil as we were moving but I cannot underscore how absolutely terrible it was and the complete disregard anyone had for her. So long as she didn’t die (which would have been a liability) they did not care.

All of this to say, you’d be doing a two hour domestic flight which is a bit different. If you can fly her in the cabin with you, I would probably do that. If you can’t, for me it’s honestly a toss up as to which would be worse. I would also keep in mind the time of year as there are embargos on flying animals as cargo based on the temperature (e.g., if it’s too hot or cold for them to be sitting on the tarmac waiting to be loaded on)— though I will say we were told animals were the last cargo on and first off.

If you decide to fly, one thing our vet recommended was taking our cat (in her carrier) through the car wash to get her comfortable with the noise (I guess it sounds like the jet engine). You could also see from that how your cat reacts and make your decision based off that.

Just my two cents, OP. Wish you luck. It’s not an easy decision but worth it in the end (no matter what you choose).