Rome FCO to Florence with Seniors

As someone older than 79, I am never sure how to take these comments. Do they have any physical limitations? If not, then we are just talking about walking and dragging a suitcase. The train would easy especially if you can catch the train at the airport. There are two a day directly to Florence. The alternative is to change trains at Termini in Rome. A little extra walking and time. The train would be more comfortable than a car. Have access to restrooms, snacks, and you could sleep some. I would go with the train unless you are absolutely certain they cannot handle the walking.

You could wait and take the 13:53 direct FCO-Florence high speed train.

Note that you won't need to use the stairs to transfer at Roma Termini, it's a terminal station. Same at Firenze SM Novella.
I think the two further tracks in Roma Termini are 300 meters away.

Elderly woman with a cane here. I travel alone, and manage trains quite well, even after a 24-hour flight from my home to FCO. I have never had the luxury of taking the train directly from the airport to Florence. I make the change at Termini. Of course, you know your own family so I am sure you will make an appropriate choice.

I’m only 67 and can walk a decent distance, but can’t carry anything at all heavy or lift my lightweight carry-on bag into trains. The thing that helps us travel at all is that my husband’s luggage is a large backpack and so he can manage my rolling bag and his backpack at the same time. Instead of first one, then the other. One person with two rolling bags is not so good on trains, we’ve found, although doable.

Have you thought about flying into the Florence airport? So nice and small, and super easy and quick to get into Florence. You might actually save money compared to using a car service.

Long ago, my grandma took her first trip to England at 80. She went with her daughter and granddaughter and GD's husband. She often reminisced that it was wonderful but she always needed an afternoon nap. As my mom got older, she traveled with her sister and they always scheduled cortisone shots in their knees right before they went. Now, I travel with my sister and it is the best!

Personally, I'd put a lot of thought into the baggage. While it is tempting to say they should pack as little as possible, they need what they need. Maybe it's a CPAP machine or extra shoes or something else. Perhaps it's better if they pack very small bags while you or your wife have something that is perhaps larger than you need so you young 'ens can take some of the burden. Just plan on it. I'd rather maneuver one little bit bigger suitcase than two little ones. Your mom and auntie might do perfectly but my experience is that travel weariness is cumulative. A direct train from FCO to Florence seems very doable. The trains are a great experience and, in my opinion, more comfortable than a car.

At 1:53p there’s a direct train from Rome’s Fiumicino Aeroporto to Firenze S.M. Novella (Florence) station (2h 30m).

If you decide to use a car service rather than the train, consider a car service we've used and will use again. The company is know as Rome Cabs, but it is definitely a car service and not a taxi company despite the name. We send an email detailing our needs and get an answer within 24 hours. Needless to say, we've always been pleased with their service.
This is the link to their site. https://www.romecabs.com/.

Thanks for your helpful replies--it is especially useful to know there aren't a lot of stairs. My inquiry was certainly not meant to be "ageist". We are just trying to ensure that my mom and aunt have the best time possible on this trip and don't start out super tired. Based on the feedback, I think we will shoot for the direct train. Is that typically something one needs to buy/reserve in advance?

You will get a better price if you buy it in advance.

Just to reassure you — the access from the airline terminal to the train station at FCO is step-free. There are escalators or elevators (or ramps) anywhere you might encounter steps. So going to the train is the same as walking to a waiting car outside the terminal.