Tuscany - 9 days itinerary help (October)

Have you considered staying at one or more agriturimos out of the main towns and convenient to wineries and other sights. They can be very simple, or offer classes or other amenities. They are relatively common in Tuscany.

For example: https://blog.ricksteves.com/cameron/2019/07/tuscany-agriturismo

IDP does have an expiration, typically good for 1 year
If you think you may drive be sure to get a new one

Agriturismo stays usually require a car

Most day trips using public transportation are single destinations. Siena, best by bus, is well worth a full day. I havne't been to San Gimignano - yet - which is also a one-town visit by bus. Others here have said you can visit Pisa and Lucca in one day by train. I believe that's if you just want to visit the cathedral campus. Besides the tower, the cathedral is beautiful and the baptistry is exquisite. There's certainly enough to see for a full day in Bologna, by train. Those are the main day trips.

The Cinque Terre are too far to make a reasonable day trip and Portofino is even farther.

If you want to see other towns, consider a few nights in Bologna. It's a rail hub, so Parma, Modena, Ferrara, Padua and even Ravenna with its marvelous mosaics are good day trips.

Christine has noted that you'd want a car for an agritourism stay. That's good if you want to visit wineries, but note that the legal alcohol limit for driving is only .05% while in the US it's .08%. Hill town visits are problematic because parking is very limited and driving in Tuscany can be challenging on back roads.