Buongiorno,
with a group of 4 adults and one youngster - you might find that you could do a private tour for the same amount of €€ - and it could be specifically tailored for your objectives.
I can recommend a driver that I have used and found to be professional, speaks English well and he is reliable, you could try asking Simone -
essemazzini@gmail.com - what the prices and timing would be like.
There are several places you can go on your own from Siena, using public transport, have a read through our article about
Day trips without a car.
Another article you might find useful is
Things to do with Kids in Chianti - which include activities that will make everyone happy. And one more article which may give you a few ideas is
Kids in Siena.
Or you could
look at this tour, which leaves from Siena and covers 3 different places including San Gim. Itis a bit long but really covers a wide range of things in the Tuscan landscape...include a wine tasting!
You might want to browse
these other tours, there may be something you like.
Buon Viaggio,
Donna Denise