Of course there’s a bar in Florence called Dolce Vita. And this is a really cool, local hang out, with retro decor and a good cocktail menu. I’d recommend coming here for aperitivo as you can enjoy complimentary bites with your drink (beware they don’t use measures here, so drinks can be very strong). It’s open until 2am so post-dinner drinks could certainly work too.
Piazza del Carmine 6r