Florence has some of the most talented musicians playing in the streets at night. I have enjoyed them immensely. Some of them are classically trained in their Eastern European countries, but are unable to get work there. Others just might be doing it to support their summer travels in Europe. I have bought a number of their CDs and I continue to enjoy them while bringing back wonderful memories of my time in Florence. You can often also find them playing during the day.
If you like 60s and 70s music you will enjoy Mercer and Peres you will often find them at the Uffizi at night.
The streets of a February evening in Florence are excellent for people watching - it was cold and brisk this evening and I just loved stopping what I was doing and just watching people going on with life. Ordinary Florentines just wanting to go home, either oblivious or annoyed at the constant throng of tourists that are in their city! I am glad they are so generous as to put up with us all the time!
Dress Code: Dress warmly and bring something waterproof! It can be damp and cold!
There are plenty of places to grab a bite to eat and relax with friends in true Italian style. Pubs and cafes are all over the place. Italians love to stroll around and socialize with each other. I looked into some nightclubs but they all seemed to attract a younger crowd.
There's not much of a nightlife in Florence, at least not like you would find in Paris or London or even Rome. Your best bet is to find a spot in an outdoor cafe and settle in for an evening of wine and people watching.
Dress Code: Florentines are very stylish but not obnoxious about it. I equate them best with New York City and its trendy areas. Everyone has a cell phone. Everyone wears leather somewhere.
For those of you who aren't interested in mingling with the party crowds or club-hopping, another great recommendation that I can think of is to stroll along the banks of the River Arno and just watch the world sail by..... It's an enchanting experience for sure and it's free!!!
I think Italian Nightlife happens on the streets. Special tip: It must be a great view from the Piazzale Michelangelo during the night with the lights of Florence to your feet...