Rome Airport (FCO) to Venice Mestre via Trenitalia

Best to wait til you arrive and buy at the station or on the app

Some tickets are refundable/changeable
Discounted tix purchased in advance are usually not refundable
Read the fine print

https://www.trenitalia.com/en.html

Station names
Roma Termini
Venezia Mestre

Are you going to Mestre? Or actually to Venice?

What is handy is that you don't have to purchase tickets for each, you can just be standing at FCO and put in Venezia (whichever station you wanted) in the machine and it will give you the best options and you can get them both at the same time. Last time, the best (and least change) option from FCO to Salerno was an IC train to Termini and then a freccia train to Salerno, with only the one change, which I was excited about.

You can save a lot of money purchasing in advance for your OTHER trips, but keep this one "in the moment" so you can buy the one that looks best and the most timely to you when you are physically 30 yards from the platform.

Going to Venice, but staying in Mestre

Katherine. Thanks for your advice. Verifying my understanding. When purchasing at the airport ticket machine, I would see the same train schedule that I would see on the trenitalia app (or website). In other words, I would be purchasing a ticket that covers travel on the Leonardo Express from the airport to the Rome terminal, and then my transfer to the Freccia train to Mestre.

Yep! I don't even bother with the app if there is a machine in front of me. It will already default to the station you are standing in and then you type in your destination. And as my experience was, sometimes there are even better options than using the Leonardo express, but it all depends on the schedule and where you are headed. Normally it will be a Leo Express to Termini and then change to your next train. There will probably be options that are different prices, number of changes, and time between trains, so take that into consideration with which one you pick.

Thank you Katherine. You have obviously been to this rodeo a number of times.

Oner last question. We'll allso be staying in Florence, then on to Naples and then wrapping it up in Rome. I'll be using the train to connect each destination. I understand (which you confirmed) that buying tickets in advance can yield better pricing options.

How much time in advance? Should I purchase these tickets from Mestre to Florence then to Naples and then to Rome about a month before heading to Italy?. Or can I purchase the tickets on the Trentalia app while in Italy and before making my way to the next destination?

Unless things have changed, there are schedule releases for tickets in the beginning of June-ish and December-ish. Some routes can have trains listed before then, I can't tell which ones why. If you buy them as SOON as they go on sale, you can save a BUNCH. As the cheaper fares get sold, the fares go up until the "day of purchase" price that you are doing when you arrive at the airport station. I was traveling from Lake Garda to Florence once on a Saturday, and when the tickets got released, there was a promotion for 2 for 1 first class seats on Saturdays, so we even saved money to take that trip! It would have been sold out if I would have waited.

You can use the app or the website to purchase in advance (I rather do the pre-planning on my computer, it's easier because you can see more and compare options with ease), but if you know when you will be traveling, get them asap. The cheapest fares are usually the most restrictive regarding changes and usually not refundable, so if you miss, you are out the money. I always aim to get to the train station 30 min ahead, so if any transit delays happen I have a buffer.

I also travel between check out/check in times to utilize my time well, like eating at my favorite restaurant near the train station in Florence at noon, get on a 1:30 train to Rome, and then arrive at my lodging in Rome 3-3:30ish.

Another to consider (if you have the time): since the train ride will be a long one and if your flight does not arrive early in the day you could stay at a hotel in Rome for the night of your arrival & take an early train the next morning.

Just curious...is there a reason you don't just fly into Venice?

I suggest flying as well. We planned to train but when I dug into the options further, I was able to save a ton of time (and a little money) by using skymiles on ITA from FCO to VCE and gets us to Venice by early afternoon instead of evening.