Rome to Siena

Montepulciano is lovely
Assisi is a bit out of the way
Orvieto would be nice

You have the option to stop at Assissi to see the Basilica, Orvieto is a great stop, there are a few charming little towns along the way like Bolsena, Viterbo Italy, and Cortona.

https://www.italymagazine.com/featured-story/day-tripper-bolsena

https://theculturetrip.com/europe/italy/articles/the-best-things-to-see-do-eat-in-viterbo-italy/

https://www.cortonaweb.net/en/