Where should we go if staying in Florence and want to see more of the Tuscany Region but only have three nights in Tuscany.
Hello gjparenteau, and welcome to the forums!
Are your 3 days after Florence or do they include your time in Florence? If that is also your time in Florence I would recommend only one day trip because Florence is worth spending the time on.
Are you restricted by train or are you thinking of renting a car?
What are your interests or points of emphasis in Tuscany?
Siena is the classic Tuscan hilltown visit for good reasons and is well worth it. Arezzo is another hilltown you can visit via train. The old town aprt is smaller and it is much less touristy but is a nice mix of more modern Italy in the lower town and old hilltown above. These can both be done as day trips from Florence.
These are both big cities by Tuscan standards but the smaller towns are harder to visit efficiently by public transport. There are many places that are willing to transport you and show you San Gimignano or other small towns near Florence which is another option.
Here is a train map of Tuscany destinations with dotted lines for bus connections:
https://www.wanderingitaly.com/maps/tuscany-rail-map.html
Hope that helps some, enjoy Tuscany,
=Tod