In response to the above comments trashing Florence, and to offer a contrary opinion of support, I would have to say that Florence is my favorite city in the whole world. I could easily live there, at least part of the year, if I were well off. I have only visited four times, and admittedly, I am an artist and my wife is an art historian, but seeing as how Florence is the birthplace of renaissance culture, has amazing museums, buildings, and art everywhere of historical import, is stunningly beautiful, and has some of the best shopping anywhere, I find it amazing that someone wouldn't like it. Yes it's crowded, but that's because it is such a draw. Yes, Siena is also beautiful, Pisa, San Gimignano, Cinque Terre, Venice and Rome are amazing in their own way, but the sweet sublimity of Florence is in my opinion, unsurpassed. Where else can you visit an apothecary and purchase cologne made by Dominican monks (i.e., the dogs of God) since the 13th century (S. Maria Novella), or visit Dante or Michelangelo's house, dine on wild boar stew or Florentine steak, or....
Ok, I'm done.