Taking prohibited pictures of Michelangelo's David (without flash).
Being sonically accosted by the University of Southern California marching band playing Gwen Stefani's "Hollaback Girl" in the Pitti Palace gardens.
And gelato. Perfect gelato.
Also on Grom's site, they give careful attention to food allergies. They have a handy chart that shows which of their flavors will work with your allergies/dietary restrictions: gluten, eggs, milk, dried fruits and nuts, and vegan.
A few weeks after we returned from Florence, we discovered we were expecting our first child. I'd give at least a little bit of credit to the Grom.