Itinerary for March

We need for someone else to confirm, but I think the early-access tours of the Vatican start in the Sistine Chapel, see some other parts of the museums, then head to the basilica. Once in the basilica, you will not be able to return to the museums unless you have a second ticket.

The Borghese Gallery requires a pre-purchased ticket (and not at the last minute). I think the Colosseum and Forum do as well, but I'm not certain. You really should pick up a copy of Rick's guide to Italy. He always provides a lot of valuable logistical information, plus there are walking tours and details about the top sights.

There are separate entrance tickets for the "Duomo" and the "Duomo Museum" (Museo dell'Opera del Duomo, Florence). I am not sure which you have purchased. The Duomo itself didn't do much for me, but the Duomo Museum has some great original items from the Duomo and elsewhere. For example, the original Baptistry Doors are in the Duomo Museum, and the Donatello Penitent Mary Magdalene.

https://www.donatello.net/penitent-maddalena.jsp

You do not mention the Uffizi gallery in Florence either, which is on most bucket lists and is amazing - but you get to choose. The Galleria is really just the David statue so it really doesn't take that long to visit.

I like your approach to limiting your commitments ahead of time. Have fun.

In Florence, the Duomo museum is wonderful! I believe your ticket also includes entry to the Baptistery, which I found to be both stunning and peaceful. If you have time, the views from Piazzale Michelangelo and the nearby San Miniato al Monte basilica are lovely.

You will definitely want to pre-purchase tickets for the Colosseum and Forum so you can choose a time to visit that works best for you. I'm not sure if tickets sell out in late March, but you don't want to risk missing out on one of your must-do's.

You are very wise to pace yourselves and allow time to explore. My husband and I did that on our first visit--and now are planning our third trip to Italy. (So maybe that wasn't so smart :)!!) Enjoy your travels!

Just to clarify NickB's post above, the David statue (the original) is in the Accademia, and there's not a lot more to see there. At least not compared to the Uffizi, which is full of masterpieces (and has a copy of David right outside). You've already bought tickets that get you into the Accademia, but if you like Renaissance art and have time the Uffizi would be worthwhile. I believe it saves time to purchase Uffizi tickets ahead, but I'm not certain. RS or another good guidebook would tell you this. Certainly a guidebook would be a worthwhile investment for a trip like you're planning.

We need for someone else to confirm, but I think the early-access
tours of the Vatican start in the Sistine Chapel, see some other parts
of the museums, then head to the basilica. Once in the basilica, you
will not be able to return to the museums unless you have a second
ticket.

We did the Pristine Sistine with Walks of Italy and this was true. I believe it is true for all the early entry tours.
Unless you feel like hiking back to Vatican Museum entrance- 20 min- and probably paying admission again, you'll have to just enjoy the parts of museum you will see on your tour.

Do you recommend pre booking any of the monuments or can we wait until we arrive in Rome?

I definitely recommend the Borghese Gallery, and it must be booked in advance (timed ticket for a 2 hour time slot) -- the Borghese was a fabulous art gallery/museum, and I think it's a must see in Rome.

The Florence Duomo tickets are only available for as a combo ticket including the Cathedral, the Museum, and the Baptistery (and the Dome) -- and you definitely want to see the Museum. Many of the original treasures are no longer outside on the cathedral or baptistery, but inside in the Museum (the doors on the Baptistery are actually copies with the originals inside).

We enjoyed the Bargello and San Marco Museums very much. They were not crowded and not massive- worth a stop.
Also enjoyed Santa Croce

Thank you all for your thoughtful reply!
I double checked that I did indeed purchase tickets to the Duomo museum and it includes the Dome entrance.
Good to know about the Galleria Accedemia. I really only purchased them for the statue of David so we can move right along there as well.

I did go back and check my tickets for the Vatican and you are all correct that we will end our tour in St Peters square. With so many other museums and galleries I think we’ll just move along and enjoy some down time in the early afternoon.

I am waiting on my Rick Steves travel guide to arrive. I found his guides as the best resource in Belgium and the Netherlands and have no doubt the Italy guide will be the same.

Thanks again!

Good plan
TBH the Vatican Museum was so crushingly crowded I couldn’t wait to get out of there and don’t know if I’ll ever go back!