Sienna as a Base for Exploring Tuscany

My advice would be to rent a car in Tuscany. Our first trip to Italy was when I was 62 and I worried about all the things you mentioned. It wasn't as bad as I feared. Learn the traffic signs and get out of the locals way. Just stay away from big cities. We even drove through Palermo and survived.

I can't give pros and cons of driving because I haven't driven in Europe, but I'd like to point out that Florence, not Siena, is the public-transportation hub for Tuscany. I suspect there are a lot more tours originating in Florence as well. If you decide not to rent a car, I think you should plan to stay in Florence during the time you plan to take most (or all--depending on where you go) of your Tuscan day-trips.

There's nothing wrong with spending a couple of nights in Siena to enjoy the vibe of that city. I don't know whether there's enough to keep you occupied there for 3 nights.

Like you I was initially spooked by the cautionary tales reported by some here regarding driving in Italy, and in fact nearly gave up on the idea before our most recent trip a couple of years ago. Decided to hang in there, though, and am quite glad that we did. We were in Tuscany for about 5 weeks - the time split evenly between Florence and driving around the countryside. By far the highlight of the trip was the time we spent driving, which we found to be an absolute pleasure once we got off the Autostrada and started exploring some of the rural roads. The bottom line is that we found that the supposed horrors of driving in Tuscany were vastly overstated. It's really not that big a deal if you just do your homework in advance, and there are plenty of online resources to get you up to speed before you get behind the wheel.
Personal opinion only, but I don't think you can properly do justice to the countryside in Tuscany and Umbria without a car.
There's an AutoEurope/Hertz office a couple of blocks from the train station in Siena which makes picking up and dropping off a rental a snap, and we never had any issues finding a parking spot in the underground lot at the station itself, which at 2 Euros per day was probably the best bargain in Italy. Helps too that the parking garage is right on the highway heading south into the Val D'Orcia making it easy getting in and out of town. Plus, you never have to go anywhere near the dreaded ZTL's that seem to cause so much angst among those unfamiliar with the local rules of the road.
I really suggest that you reconsider renting a car - you'll be glad you did.

I have not driven in Italy, so can not advise you on that except to say that it will be easier to visit many town and enjoy the countryside if you have a car. And also easier to move lodgings after 2 or 3 nights in order to reduce your windshield time.

Siena would be an easy city to avoid ZTLs because it is a walled. Don't drive through the gates. If you have a car and stay there, you can easily find lodging close to a city gate and park outside the gate. You can take a bus into the walled area if your lodging is too far to walk.

If you have not done so already, buy your guide book for Italy and check our the Planning Map that comes with it. It will show the train lines and major roads. Decide what towns you want to visit. Use Google Maps to determine travel times by car and mass transit. This information will guide your drive v. bus and train choice.

From Siena to Assisi is 96 minutes by car, but over 4 hours by mass transit. Assisi has many steep lanes with stairs incorporated into the walkways. In contrast Siena is also hilly, but not so many stairs.

I've spent a fair bit of time in Siena (sadly not for a few years), and it remains probably my favourite city anywhere.(So I am biased)

Having said that, it is not a great base to explore using only public transport. You can get to San Gimignano and Florence easily enough by bus, and I have gone to Arezzo (also by bus) which was worth the trip. You can get to Florence via train, or Pisa/Lucca if you change at Empoli. I have not found driving in Tuscany to be difficult - particularly if you are already aware of the ZTLs (and for me, Italy is the "Wrong side of the road" - some of the drives are quite stunning. That said, unless you have parking as part of your accomodation then parking can be very expensive (I seem to remember that even 10 years ago it would cost in excess of €25 a day to park in one of the major car parks.)

As others have said, Florence is a far better choice for transport and would give you many other options - but I would not avoid Siena based on that. With a car, I have been able to go to many places from Siena including Assissi, Montalcino, Montepulciano and Lake Trasimeno.

We have been on five trips to the Chianti region very near Siena. You need a car! We have stayed in Radda, Panzano and Castellina as well as Florence, and farther away, in Cortona and Lucca. We used them as bases to explore the surrounding areas. We never have gotten a ticket for a ZTL in these areas. And we always found parking in Siena even during the Palio.
We found the Italians to be excellent drivers. If they drive faster, they still know what they’re doing. Driving on the Autostradas( like our interstates) is no different than in US. We have taken a few trains and do not like schlepping luggage on and off them and we always take 22” bags. Never have taken a bus there. Even if public transportation goes to a town you will be restricted by their schedules.
You will want to travel on SS 222, the historic Chiantigiana, the route that connected Siena to Florence where the charming towns are located.
A driving tip:? Copy a page from a Rick Steves’ guide book for European driving signs,i.e., one way, no parking, etc and tape it to the car’s dashboard. I always do that.
You will glad you rented the car. We always book our car rentals through AutoEurope.

Here's another vote for driving.

Like Robert, we had planned on driving, but almost got scared off with all the horror stories posted here. Luckily I decided to take them with a grain of salt. We had a marvelous time that would have been impossible without a car. All you need is some common sense and a little education before you leave.

We used Greve as our base, staying in a wonderful agriturismo (Castella di Verrazzano). Siena would also work as a base, though it might be a little more involved working out parking and getting in and out of the city. However, we had no problems when we visited Siena by car, only the heart of the city is ZTL and you can either stay or park outside of the ZTL.

To answer a couple of other questions you have:

d) how many small towns can be done in a single tour?

With a car and Greve as our base, we found the maximum number of towns we could visit in a day was two. One day we did San Gimignano in the morning and Volterra in the afternoon. We dedicated an entire day to Siena and Florence. We took a commuter bus into Florence at the recommendation of our hosts and it worked out well.

d) is Assissi doable as a day trip?

I guess technically it could be done, but Assisi is in Umbria, not Tuscany. We had considered trying to go to Assisi, knowing it would be a very long day. We also thought about visiting Montepulciano and Lucca. If we had another week, we might have tried, but there was just too many things we wanted to do and not enough time to do them. Given your amount of time, I would save Assisi and Umbria for another trip.

Again, don't get spooked by the horror stories. ZTLs are well marked and easily avoided. When in doubt, assume anywhere withing the walls of a hill town is ZTL. We found plenty of parking outside the walls of all the hill towns we visited. Plan your trip in a way that when you stay in Florence, you won't need a car. It will be an inconvenience and unnecessary.

Just remember that people who have a bad experience are more likely to complain. This is rural driving, and you can prepare in advance (ZTL just means look for a sign, don't drive past the sign, park and walk). There is no reason to deprive yourself of the experience out of anxiety. If it was easy, these towns would be impossibly overrun! I would have far more trepidation about trying to plan a limited amount of time in an area not well served by transit. Now if you really just don't want to drive, there are thousands of alternative places that are well served by train and bus, and that are close to where you will be--Emilia-Romagna and Liguria are two places that are great without a car.

Here is a short list of towns in Tuscany to visit by bus and train from Siena.

These towns are easily accessible by bus and train. Some towns I've combined with others. (B=bus, T=train)

Siena-Colle di Val d'Elsa ( B 30m)-San Gimignano (B 35m)-Siena (B/T 1H05m)

Siena-Montereggioni (B 18m)-Castellina in Chianti (B 30m)

Siena-Radda in Chianti (B 55m)

Siena-Buonconvento (T 28m)-Monteroni d'Arbia
(T 12m)-Siena

Siena-Rapolano Terme (T 37m)-Asciano Mont Oliveto (T 10m)-Siena (T 26m)

Siena-Sinalunga (T 53m)

Siena-San Quirico d' Orcia (B 50m)

Siena-Pienza ( B 1H05m)

Siena-Certaldo (T 39m)

Siena-Pisa (T 1H46m

Even if you decide on 1 hilltown a day, there's plenty to do. Look at the towns to see what interest you.
Be sure to check return times by bus carefully.

I’ve driven many times in Tuscany, the speed limits on these rural roads is 50-70kpm ( 31-45 mph). So, there are speeders, but all you have to do is pull over to let them pass.

You will see more towns by driving, 2-3 a day.

For info on driving

https://italybeyondtheobvious.com/

Scroll down to their driving in Italy and sign up for PDF info.

Your gracious replies have been so very helpful. You have given us the confirmation of what we probably already knew. We just needed reassurance from the personal experience of others--that renting a car is not only doable but the best way to visit Tuscany and Umbria.

My husband and I have discussed your comments and plan to rent a vehicle from Auto Europe with no deductible coverage. We are staying outside the city walls of Sienna with free parking and easy access to bus transportation into the city as needed. We will make use of your practical suggestions and are optimistic that after 4 cancelled trips, spring 2022 in Italy will actually happen.

We have rented cars in Mexico many times, once in Spain, and in several locations in Australia, including Tasmania. Driving in some areas of Span was fine in some areas, more stressful in others. Driving in the other countries has been great.

Thank you so much in restoring our confidence and helping us figure things out. This travel community is awesome!