Has anyone been to the thermal pools at Bagno Vignino near Siena?
We will be near there in late October. Is it worth taking a side trip?Is it expensive,& lastly is it possible to get there by public transport?

I'm thinking you mean Bagno Vignoni. Here is an article that describes the town and facilities (you can google for more info)-

http://www.slowtrav.com/ginda/bagno_vignoni.htm

You will need a car. There is a small public/free pool down the hill from the town.

Is it worth a side trip? I feel it is if you combine it with visits to other towns in the area, enjoy beautiful countryside and if you really enjoy thermal pools. The town is very small with a few good places to eat.

Yes, I've been there, and to many other spas in Italy. I love spas! I don't remember how much it cost, but I don't remember it being expensive. You'll definitely need a car to get to it and most other spas. It's 50 km from Siena.

Another one in the area - Montecatini Terme near Lucca is one of the primo thermal resorts in Italy - a park-like setting dotted by thermal establishments - can go by train via Pisa and Lucca.

There is a natural thermal pool that you can stick your feet in for free just down the hill from the town. If you want to pay for spa services like a mud bath, etc. then visit www.albergoterme.it for more info. Nearby, in San Casciano dei Bagni is the gorgeous Fonte Verde Spa, which offers a host of spa services. www.fonteverdespa.com.
I always have a car in Tuscany so no idea about public transport.

Thanks for your input,we will not have a car,nor do I wish to hire one so I will try for Montecatini Terme,Lucca is so lovely I did not know it had any thermal resorts nearby, so it`s doubly worth visiting.

Bagno has three pools, the central square one which is illegal to enter but I saw a reporter on BBC tv in it the other day, The one at the Post hotel which is great, clean, you need to wear a little hat and the pool is lined with white mud low cost say 10 euros (can't remember but its in that region). The one at the bottom of the valley is open to all and free bathing but not as warm (October would be tough).

My sister stayed at the Post last year for 2 days and had a great time