10 day trip to Italy for a family of 4

For Pisa, we just added it as a train stop. Parked our bags in a luggage storage around the corner from the train station, took a lovely easy walk through Pisa, came up on the truly memorable tower, walked around, went back to the train and went on to Rome.
We did not expect it to be as fun as it was. And it is easy to do in half a day.
The trains were not a problem.

The good news is that once you leave the waters of Venice trains will get you everywhere you need to go. Fast train from Venice to Florence is about 2:15 and Florence to Rome is even a little faster than that. The only bad news is that the section from Bologna to Florence coming from Venice is largely in a tunnel to avoid the mountain climbs in between. The ride from Florence to Rome will be more scenic running through Tuscan and Umbrian countryside for much of it.

The train from Florence to Pisa is local regionale train that will take about an hour or so. I recommend going early and reading up on the wait for tickets to actually go up in the tower while touring the other parts of the site. If your schedule is not completely packed with Florence sites I'd recommend Siena as another possible trip, but your schedule seems pretty tight already.

You can buy fast train tickets ahead of time and save money (sometimes significant amounts) by trading price for flexibility and locking in a specific train and time. All fast trains have assigned seats and different classes where regionale trains are all second class and the price never changes so you don't need to buy then until you need them.

The two trains companies are Trenitalia - the state run trains - and .Italo the private company that only runs fast trains between big cities.
https://www.trenitalia.com/en.html
https://www.italotreno.com/en
Both companies have apps I recommend getting the Trenitalia app and creating an account on the website. I can store tickets, check schedules, buy tickets and track trains in real time.

The website (The Man in) Seat 61 is great place to learn about trains, travel options, specific stations and all kinds of things train.
https://www.seat61.com/Italy.htm

Book must see things ahead of time when you can and have a great trip,
=Tod

In reverse order:

Each of you bring a sweater (or fleece liner top or sweatshirt) and a light-to-medium jacket. Wearing one or both gives you better comfort options than bringing just a parka.

Consider a cooking class in Florence! Get a Bistecca Fiorentina (Florentine Steak) dinner one night. It’s a big steak prepared for the table, and will be rare. I recommend the Antico Ristoro di Cambi, https://www.anticoristorodicambi.it/en/ on the Oltrarno side of the Arno River, but this Forum will provide lots of additional suggestions. For seafood, also in the Oltrarno neighborhood, it’s Burro & Acciughe. For a special dinner, make a reservation for La Leggenda dei Fratti https://laleggendadeifrati.it/en/ (recommended by Michelin, but without a Michelin Star).

Skatepark? I can’t offer any specifics, other than than skateboarders who were riding around on a piazza in front of a church. Where’s he planning on getting a skateboard?

For the Colosseum in Rome, look at getting an extended access ticket to the Underground passageways and/or the Colosseum Floor, not just the general admission to the seating area.

At Pisa, the leaning tower is part of the Field of Miracles. As long as you’re there, also check out the adjacent Baptistry, which has amazing acoustics, and the echo effect is demonstrated on a regular schedule. Right next door is the Camposanto, with amazing 13th Century fresco murals, although that may or may not of as much interest to your teens. It would probably make an amazing skateboard venue, if that was actually allowed ;-)

You could take a train to Pisa as a daytrip from Florence and back, then later take a train directly from Florence to Rome when you’re done; or, stop at Pisa on your way from Florence to Rome, taking trains the whole way. The train station at Pisa has a baggage storage, where you could stash your suitcases while you go visit the Tower (and potentially its fantastic neighboring sights), but there’s a charge for that storage, and it’s not necessarily “Service with a Smile,” but it gets the job done.

Consider splurging for First Class on the train - nothing shady there! The entrance at the Florence Train Station has a reputation for potential pickpocket lowlifes (we had no problems); see the Rick Steves guidebook for further advice, if you have concerns.

If you go inside St. Mark’s Basilica in Venice (highly recommended, along with its Treasury), remember that no exposed knees or shoulders are allowed. In March, that’s probably not going to even come up, but people get turned away in the summer for not adhering to the “modesty clothing” policy. Backpacks aren’t allowed. either. so plan accordingly.

Check to see if skateboards are allowed on the Lucca historical wall - a popular place to walk & bike! Lucca is very close to Pisa.