5 days in Tuscany

Traveling with so many people is going to be difficult as there will be differing opinions on what to see and where to go. Whoever is planning such a trip might want to consider working with a travel agent that specializes in Italy.

First of all, most people flying into Florence will usually fly through a gateway European airport and then catch a connecting flight into Pisa. Then they'd take a train over to Florence. Herding so many people through airports and to one place would be especially difficult. Have you considered traveling in parties of 4 and meeting somewhere in Tuscany at a given day and time?

Five days is really not enough time to see Tuscany. Florence is really a 3 day minimum stay by itself. Siena and San Gimignano are worth seeing. We especially enjoyed driving thru the countryside to Volterra too. The other places you note are secondary--only if you have time. Montalcino is the tops for red wines and a great place to tour.

We stayed between Certaldo and San Gimignano--about 4 miles from Poggibonsi. Virtually every farm in Tuscany has rooms and apartments for rent as a secondary source of income. But finding one place that has so many rooms for your party may be difficult. That's why I suggest using a travel agent. Maybe they could find you a villa that comes with a great Italian chef.

Good luck in your planning such a trip.

Please do what poster David suggests and hire a good, knowledgeable travel agent, a Tuscany specialist.
You need much more time to see and do what you want in Tuscany.

Only 5 days? Are you coming from North America or someplace in Europe? Because considering the flying time and jet lag, I wouldn't take a trip to Italy from North America for a period shorter than a full week.

Welcome to the forum!
Question: Will you have children with you? That is a whole different trip than a bunch of adults.
Some basic rules to follow is that you lose one day with each move, especially with that many people. You usually need to check out of one place by 11AM and can't check into the next place till 3PM, there is the packing up, the driving/travel, eating, bathroom breaks (For this many people I am thinking lot's and lot's of stops for potty breaks, especially if you have little ones) etc.
Personally I would base in Florence for all 5 days and hire a driver/tour company to take you on day trips to various towns.
There is a company called Walkabout Florence that will take you all on a bus for a visit to Sienna, San Gimignano and Pisa, with a stop at an organic winery for lunch.
You could book an all day winery tour.
Book another day trip to Montepulciano.
Florence itself has so many options to see/do.

Here is a website that has many many day trips you can book (but book through the actual tour company) https://tinyurl.com/2hv5f3pd

I agree with the PP who stated that they would not do the whole of Tuscany in 5 days. Maybe just Florence with a day trip thrown in.

I appreciate all the advice. We are Greeks, Italy is a pit stop for us, hahaha.

Transportation will be a major issue, regardless of where you stay. Many people spend three hours or more in the car each day during a Tuscany visit, regardless of where they sleep. Even in May, parking five cars at the same time can be difficult in a place like San G. Have the families already agreed how many rooms and beds they need? Do they want air conditioning or a pool? I recommend as few hotel changes as possible. Because Florence is good for several days itself, you may need a firm agreement in advance on what to see there.

There are also issues with organizing 15 people to behave like a group tour, when they think they are traveling independently. The American term is "herding cats." One reason to use a professional is so that "it isn't YOUR fault."