Suggestions for side trips from Florence

Sienna the long-time rival to Florence is a worth-while day trip for sure with its massive piazza del Campo site of the annual Palio and the many prideful neighborhoods give it a distinct touch. Its architecture is midieval versus Florence's renaissance era, the Duomo was planned to be bigger than St.Peter's in Rome but the Black Death halted those ambitions, impassively sized nonetheless.

Lucca with its massive medieval wall surrounding the city center is another worthwhile day-trip; I found it fun to just wander around the narrow streets and walkways. Bicycle rentals allow you to enjoy some time along the top of the wall, maybe grab some picnic fixings. The rich foods traditionally a hallmark the Lucchese could taunt over the bland Firienze cuisine, be sure to eat the ravioli-like Tortelli Lucchese or, any of the egg-heavy (distinctly rich yellow) pasta.

You may also consider Pistoia with its many Romanesque buildings helps differentiate itself from nearby Florence. Pistoia is recently more well known for its chocolate production, there's many confectionary shops specializing in various chocolate types as Pistoia and its surrounding villages are the center of the 'Tuscan Chocolate Valley'

As for Pisa, I personally found the leaning tower to be massively overrated. No offense to the Pisani, the town itself is clean and pretty but, I found the attraction of the leaning bell tower to be a disappointment, and the vast majority of people visiting were there to create a funny picture and check the box off their must-visit list.

For an easy side trip, I recommend Fiesole . The bus leaves many times during the day and it’s a very short bus ride up the hill. Not very crowded and the temperatures aren’t as hot as in Florence.

Fiesole, Prato, Arezzo.... I really like Arezzo and have gone several times. Pisa is really just the tower but of course it is unique. I've been to all of the places mentioned and Fiesole is the closest (bus from San Marco square) but Lucca and Arezzo are my favorites. I think it is better to spend the night in Siena because there are so many people that come during the day you can better enjoy it early or late before the busloads of people come.

I beg to differ with the poster above. Pisa is not “just a tower.” The tower is part of a complex, the Campo dei Miracoli, which includes a stunningly beautiful cathedral and a baptistery. When we visited, I felt that though the tower is so recognizable, there was something different and special about seeing it in reality.
I think half a day would be sufficient for a visit. It could be combined with a stop in Lucca, perhaps.

In case you decide on Siena, please note that taking the bus there is faster and easier than the train - you can disembark at the Piazza Antonio Gramsci, which is fairly central.

If anybody cared about, Pisa has a national museum considered one of the best in Europe for medieval art. Were this museum anywhere in the world people would travel to visit it, but being Tuscany so rich in sights, the museum is just a minor sight unknown to tourists and Pisa is considered just a tower.

In Tuscany, you just have to look closer to find sights. I was sent in December to organize a concert in Cascia church near Reggello (province of Florence). Cascia is a rather remote village and probably you never heard about them, but they have a new museum displaying the very first picture by Masaccio and one of the first pictures in history, maybe the very first, displaying a painted perspective. The museum is actually the picture collection of this unknown country church.