How lucky you are to have a month in Italy!
I am assuming this is your first visit?
Exactly how many nights do you have on the ground in Italy? You say a month so I will assume 28-29 nights?
We’ve visited most of the locations you have planned- other than CT- and plan to return to Tuscany again in 2022.
First- there is no need to get your car at the airport- it will cost more and is out of the way. You can pick up car as you leave Florence from one of the city center locations- we picked up at Hertz Sansovino, the other is Borgo Ognissanti near SMN train station. We always use AutoEurope for our rentals. Be sure you read all you can find about driving in Italy- ZTLs, parking etc. All drivers will need an IDP- International Driving Permit- you can get at your local AAA for a small fee.
Do some searches here on forum for “renting car in Florence”, “driving in Tuscany”- there is tons of really important info especially on how to navigate out of Florence. It was much easier than I expected.
I would try to cut out 1 and 2 night stays. Where you have slotted CT in your plans doesn’t make a lot of sense to me and if I was going all the way to CT I would stay 3 nights- your arrival to CT day will be mostly spent getting there, especially if you are coming from San Quirico area. Then from CT to Rome is a long haul.
Pisa only needs a few hours, I wouldn’t spend a night there.
I see nothing wrong with splitting your Tuscany stay between 2-3 locations. We enjoyed Siena very much- stayed 2 nights and yes we drove- there are a couple really nice hotels with easy access parking (Palazzo Ravizza- fantastic terrace with views and just steps to Campo, another is Hotel Athena). I don’t think we would have liked Siena nearly as much if we had just day tripped. The evening was delightful. True that driving in to Siena was a bit dicey- but we managed. We didn’t do any day trips from Siena- just parked the car.
I’d try to simplify/shorten all of your transits.
Something like this:
Venice 4 nights
train to
CT- 3 nights
train to
Lucca 3 nights- day trip to Pisa
train to
Florence- 4 nights- this is only 1 hr 20 min trip so you could drop 1 night here, you’d still have almost 3 full days for Florence
Pick up car as you leave Florence
Now you are in Tuscany countryside- the choice of where to stay is yours.
You could do 2 nights Siena- no day trips
then move to
Volterra- 3 nights- day trip SG, Certaldo, etc
then move to
San Quirico area 3 nights- day trip Montepulciano, Pienza, Bagno Vignoni, etc
(We stayed in and LOVED Montepulciano but it’s also a pain to get in/out- next trip we are staying in Pienza)
Or pick 2 places and stay 4 nights in each. Or drop 1 night from Florence- pick 3 places in Tuscany for 3 nights each…
That is 22 nights so far.
Drop your car in Chiusi (30 min from Montepulciano) and take the train to Rome (2 hr ).
I like to use www.rome2rio.com to plot routes and get an idea of transit times and options.
Happy planning!