I've been lucky to have been to Florence three times in my life; 2002, 2008, and 2015.
Some of my favorite tour highlights have been the following:
Cathedral of Santa Maria del Fiore
Galleria dell'Accademia (home to Michelangelo's David)
Basilica of Santa Croce in Florence (Galileo's tomb )
The Baptistery of St. John
I've also enjoyed the Gold Market to shop and look around and there's a great leather store attached to it as well however I can't remember if it's separate company or not.
In 2015, I was on a Disney Cruise and ended up eating at a place called IL Gatto E La Volpe, the prices weren't too bad and the food was pretty good. It was one of the best local meal I had on my trip. If you're in Florence and have the time i highly recommend eating there.
To me Florence is very rich from the Renaissance age and has a lot to offer with art and sculptures. I always enjoy seeing Michelangelo's David however if you can't get into the Accademia Gallery you can see a replica in Palazzo Vecchio,
If you've been to Florence and have a favorite site and/or place to eat, please leave a comment.