I recommend seeing: the duomo, the boboli gardens. Avoid….um, i can’t think of anything unpleasant, its a very nice city. Its quite inspirational. A good restaurant i’ve been to is: Gusto Leo, 8/10 Via del Proconsolo, which is open from 8am-1 at night. Its near the central train station. I’d recommend chilling near the river, or also in boboli gardens. Enjoy your trip:-D