Advice for a Family of 4 Hitting the Big 3

Great itinerary- smart to fly in to Venice, out of Rome
I would probably give Venice 3 nights (take from Florence). Venice is so unique and your first day is jet lag so you really only have one full good day to experience.
Take a look at Row Venice- kids will love it. How old are the kids?

Florence could need 2 full days (3 nights) itself unless you are not huge museum goers- in that case 1 full day can work. Each day trip is full day/night.
Combine Pisa with Lucca by train- very easy.
Not sure if a coastal visit makes sense, time wise and weather wise in March but can be done.
A day trip to small hill towns in Tuscany might be easier/more predictable.

Florence 4 nights (major museums closed on Monday)
Day 1 arrive by noon. Historic center walk, etc.
Day 2 Museum and market visits
Day 3 Pisa and Lucca
Day 4 Day trip to coast, hill town or more Florence

Trains in Italy are quite easy. You will be taking direct fast trains between Venice-Florence-Rome. You can book tix in advance for discounts.
Day trip to Pisa etc will be regional. No need to book in advance, price never changes, can’t sell out (so day trips can be decided once there- see what the weather is like)

2 train companies
Trenitalia is the state run official train company
Fast trains and regional
https://www.trenitalia.com/en.html

ItaloTreno- private company- fast trains only on select routes.
https://www.italotreno.com/en

Both have easy to use apps

Station names:
Venezia S Lucia
Firenze SM Novella
Roma Termini

Once you settle on actual itinerary and book lodging we can help you with trains. (And vaporettos in Venice!)

Lodging- do some searches here on the forum- filter by Type and Date
There are many recommendations for all 3 cities.

That’s very helpful! Our boys are 15 and 12.

Christine has some excellent suggestions and information. I know from your posts that your DH has a real interest in seeing a coastal village, but early March is really early. Weather is unpredictable and many of the tourist amenities wont have opened for the season yet. A combo of Pisa and Lucca would make a great day trip. But if he insists, and if you leave Florence early in the morning, you could see Pisa, then train to one or 2 of the Cinque Terre villages before returning to Florence. But it would be weather dependant and would be a really long day. Keep in mind how early it gets dark in early March

Another vote for taking a night from Florence and giving it to Venice or another locale.

I just mentioned in another post that I liked Hotel Silla in Florence. I enjoyed Pensione Guerrato in Venice and traveled by the Alilaguna from the airport. In Rome, I stayed at the Hotel Aberdeen (quieter rooms are toward the back). Good luck with your planning!

Some lodging reocmmendations as my family w/ two teenagers like yourself on a similar trip next month:

• Florence: Hotel City - Just a couple blocks from the train station. They have a family suite that is reasonably priced and has a separate attached bedroom for your kids.
• Venice: Red House Company - Professionally managed apartments with multiple options. See what fits your budget. An in between option for those who might be gun shy on Airbnb but need more room.

As others have suggested, transferring a night from Florence to Venice would be a wise choice. Once you have your date parameters set, you'll want to start booking some things (Tower of Pisa climb, David, etc) far in advance. Go to those sites now to get an idea of how quickly slots fill up and how far in advance they become available.

I agree with everyone who recommends taking a night from Florence and adding it to Venice. We spent 4 nights in Venice, and it wasn't enough. Venice really is like no other! It is amazing with interesting and unexpected sights around every corner. Stay in the Dorsoduro neighborhood to escape the crowds. Hopefully, early March won't be too crowded. We loved staying at Hotel Agli Alboretti. It's a one-minute walk from the Accademia Bridge and Accademia vaporetto stop. About 20 minutes from San Marco Square. And 5 minutes from the Zattere (promenade) on the Guidecca Canal.

Suggest Rome 5 nights, Florence 3.

Rome has so much to see. At a minimum do St. Peters Basilica, the Sistine Chapel, the Forum, the Coliseum, the Pantheon, Trajan's Market and the Piazza Navona.

Everyone is giving you great recommendations. I recommend you take a calendar page and fill in your arrival time, hotel check in/check out times, estimated train times for each city as well as your flight out….to see how much time you will actually have to see the sights and then fill in the activities by priority. Travel between places takes longer than most anticipate and jet lag the first day means you’re all going to be walking around in a daze, if you’re like most people. I also prefer more time in Rome especially with teens. And taking a day trip to Pompeii at that time of the year would probably be more enjoyable than the weather you may experience in the Cinque Terra.

Pompeii is awesome, and a day trip there from Rome can be done, but that is a very long day. If you want to see an ancient Roman town, other than the sites within Rome itself, Ostia Antica is a good, much closer alternative to Pompeii, and you can do it in a half day trip from Rome. There is so much to see in the Naples area in addition to Pompeii that I think it’s better to save that for hopefully another trip in the future when you can spend the time there it deserves, and focus on Rome for that part of this trip.