Yes, I've been there two years ago and I absolutely loved it. If you're in Pisa, you might want to try a Lucca night trip, which has a magnificent old city centre. Lucca is pretty close to Pisa. Go there at about 5 PM, have a walk through the center and then have supper on the central Piazza Antifeatro.
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When you're in Florence, you can't miss the Duomo, which is very impressive.
When you walk from there to the Ponte Vecchio, you'll pass a square with some magnificent statues. The best view over the city is at the side of the Ponte Vecchio on a hill. You really should go there for the view and if you have enough funds, you really really should try the restaurant. Bloody expensive, but quite memorable in both food and royal feeling.
If you don't mind a drive, go south of Florence to the Chianti district. Truly amazing countryside, a nice drive and great small villages.
BTW, on the way from Pisa to Florence, you can also visit the house where Leonardo da Vinci was brought up. Where? Well, in Vinci of course.
Have fun! I know I did.
