Airport choice: Rome vs. Florence?

It depends on the rest of your itinerary. Typically people recommend open jaw routings, where you fly into and out of different airports. In any case, you should typically spend the night before your flight home in the same city as your airport.

I will assume that your current itinerary allows you the option of being in either city the night before a flight to Amsterdam that will connect to a flight to the US. Is that correct?

All else being equal, I'd rather fly out of Florence, for 2 reasons. First, the airport is close by, and is easy to get to quickly by either taxi or tram. Second, it's a fairly small airport, so check in and security is easier. While FCO takes quite a bit longer to get to from Rome, and is big enough to take longer to get to the gate. IMO, the big advantage with FCO, especially in the colder months, is the much lower likelihood of the fog or wind delays that can cause delays in Florence.

If you do choose Florence be sure to get there two hours ahead and not assume it is not necessary because it is small. We had a 730 am flight and when we arrived every plane was being checked in at one counter with 3 clerks and the line was over 100 long. We thought we were being silly for getting there so early -- lucky we did.

We flew out of Florence to Lisbon in March 2025. We had a 12:20pm flight and took a taxi from our hotel a few blocks past Santo Spirito (Oltrarno) the ride was about 30 minutes. There were 4 of us with luggage so we opted for the cab but we could have done it using public transit. The airport was relatively small and very manageable to navigate and we had no problems with the flight. BUT, as I was researching on RS forums someone mentioned that flights are often delayed or cancelled because of high winds in Florence and sometimes people have to take a bus to Bologna's airport which doesn't have the same wind problem. I have no idea if this is true, and I only read it in one post but I was a little nervous that we could have flight delays. I suppose you could easily check the on time history of flights to see if there's any truth to that.
On the other hand, I've flown out of Rome several times. It's a very big airport, with lots of shops and restaurants but it's quite a hike to get to the actual gates. And if you're coming from the city you have to leave time to get to the airport, the fastest way is the Leonardo Express from Termini station.

Thanks to all for your helpful information.

It totally depends on your itinerary.

Florence airport is very close to the city center and is very small compared to Rome, so there is nothing to navigate, some rich Americans live in mansions that are larger than Florence airport. The runway is very short so it is subject to possible delays or even cancellations during high winds or fog, however that is not really a thing at the end of May. I’ve flown in and out of Florence many many times, but the only time I had to be bused to Bologna was because of a mechanical problem with the plane. If you were traveling at other times of the year, then high winds or fog could have been an issue.

Check in lines appear very long for those who show up long before departure, as the check in positions open no sooner than 2 hours prior to departure and at the start there is only one agent behind the desk. But I’ve learned that the later you show up the faster the line goes, because about 90 to 60 minutes prior to departure, they increasingly add agents to the check in desk. It’s up to you, but there is no reason to show up more than 2 hours prior to departure. As I said the line seems long but planes out of Florence can only be regional planes (like the A220, A319) that can’t have more than 130 passengers or so because of weight limitations due to the short runway, so you will certainly make the flight even if you show up 1 hour prior.

We did a trip to Florence, Siena and a tour of Tuscany and Umbria last year.
We flew into Rome, since Delta had a direct flight from Atlanta into Rome. If you fly to Florence, you must fly into another airport in Europe like Amsterdam.