We're visiting Florence this September and wanted to visit a Terme. I prefer to visit a place obtainable by public transit. We visited a Terme/bad when in Germany and one of the highlights of the trip. Any suggestions?
I am not sure about public transit on any of these !
But, look at mapitout-tuscany.com. Bagno Vignoni, Saturnia, and Petriolo.
Montecatini Terme is about an hour from Florence by train. The spas are on the main street leading from the train station. We actually based ourselves there when visiting Tuscany because of it's train connections and because it's a very historical town with some amazing spas.