Halfway between Pisa and Florence, there's a cute little day-tripper town called Lucca.
It's famously surrounded by huge Renaissance-era walls, which was turned into a public promenade. You can rent a bike right outside the train station and bike along the walls for an afternoon, and they've done a really nice job turning it into parkland.
The town itself is quaint, and as luck might have it, it was not as overrun by tourist as expected. The weather was fantastic- autumn in Tuscany is really one of the most magic things in life- and the gelato was sustaining in the warm afternoon pre-wine time.
Uniquely, the Roman amphitheater here had been transformed into the town's main square, the Piazza dell'anfiteatro, and you had a huge, sunny elliptical-shaped space surrounded by sun-baked facades and cheerful cafes.
"Cafe", in this case, being code for, "yes, we serve wine."
We were a bit harried as we had planned on being in Lucca much earlier than we actually arrived (Thanks Italiarail!), and we had people to meet in Florence, but it's a great place to see. It seemed like it was one of the few places in Italy that wasn't built on a mountaintop or steep hillsides, so you see a lot more bicyclist here than other cites.