Happy Hours in Italy is very common and in Florence as well. The concept is a little bit different from US where you may have a discount on drink during happy hours. Here is quite common that the bar from 6 to 9 pm offers some snack and appetizers to clients who buy drinks. Usually in most of places there is a are buffet with a choice of products. Cocktails in Italy are stronger than US or UK...be careful when you drink the first one!!

In Florence the most popular bars famous for their Happy Hours (APERITIVO in Italian) are the following:

Capocaccia - Lungarno Corsini - Very nice bar with music and faboulus view of Ponte Vecchio. Frequented by many locals from 21 to 30 yd. The have great snacks! 2 plates with different kind of cheeses, one plate with parmesan cheese, 2 plates with different kind of salami, prosciuto etc and 4-5 different pastas. Aperitivo hours: 7:30pm-10:30pm. Price as of September 08 was 9 euros.

Colle Bereto - Piazza Strozzi - Latest bar in Florence, ideal also for a quick lunch. It's a sort of VIP place with a nice terrace. It's easy to find a nice party there. Frequented by many locals from 25 to 35 yd.

Negroni - Via dei Renai - One of the oldest bar in Florence (now completely renewed) where invented the famous cocktail "Negroni". Same target as Capocaccia

Dolce Vita - Piazza del Carmine - Cool place frequented by 30 yd people, main local people.

Oibó - Right accross Piazza Santa Croce - Greci 1A -  Mainly locals in the 25-35 age range. Very similar to Capocaccia. 8 euros.

Sant Ambroggio Enoteca - Synagogue area - Piazza Sant Ambrogio. Very local, easy going atmosphere. Different salads, cold cuts, dips. 4 euros. Aperitivo hours: 6:30pm-9:30 pm.

These places are also nice for a late drink after dinner. During summer and weekend are usually very busy.

Other tips: The price of the aperitivos as well as the content vary greatly from place to place. Be aware that in many places the price of drinks is higher during the happy hours and if you want to have only a drink and not eat or a second drink they will charge the full price of the aperitivo.