Just got back from a rental in FCO.
I'm PC and i booked a class with Gold Canopy. According to the Hertz website, there a Golden choice (similar as ultimate choice in the states).
Fyi, there isn't any free choice. I get what you rented, or in my case a free upgrade because of my PC status.

Also, they put full fuel option as standard on the receipt. Which can be confusing and expensive, but you can just ignore that and fill up the tank yourself before returning the car.