If you need a movie fix while visiting Florence and can't make it through an Italian film, the Odeon Cinema near Palazzo Strozzi shows US films in what they call "Orginal Sound" on Monday, Tuesday, and Wednesday nights during the fall, winter, and spring. This isn't a multiplex - there is a single film shown, and usually it is featured only one night - though more popular films sometimes get two nights. There are typically three screenings starting between 4 and 5 PM with the last show usually starting around 10:30 PM. You can see the current schedule here.
The Odeon is a great art nouveau theater with a large screen that was built into the renaissance Palazzo Strozzino in 1922. On the ground floor the seats are large and plush, but up in the balconies it can be a little tight. There is a 5 minute intermission at the midway point of the film, which is a good time to grab a drink - you can actually buy beer at the theater along with other beverages - a cultural twist that we enjoy :)