What is the most scenic driving route in Tuscany?

For a first trip, I would choose the Chiantigiana (SR 222), between Florence and Siena : it crosses the Chianti among the vineyards, olive groves and stone villages. The route is about 69 km en passant par Greve in Chianti, Panzano, Castellina, Radda and Gaiole. It's not the fastest itinerary: the road is winding and stops easily lengthen the day. Plan for half a day at minimum if you want to stop, more to visit several towns or have a leisurely lunch.

If you'd rather picture open hills, cypresses and country roads, the Val d'Orcia might suit you better: it connects for example Pienza, San Quirico d'Orcia and Bagno Vignoni, with a detour to Monticchiello. It's less a single road than an area where you can take your time and follow the small roads. My choice would therefore depend on the landscape you're looking for: SR 222 for the Chianti vineyards and villages; Val d'Orcia for the open panoramas. In both cases, avoid relying solely on the driving time given by the GPS: parking and crossing the old town centers takes time.