I'm not an expert in Florence, I've only been there a few times. However, there are two Hiltons; the main one, Metropol, over an hour walk from the center (e.g., Ponte Vecchio) and the Hilton Garden Inn, about a 45 minute walk.

Neither is ideal because you will not be able to find them at 10:30 PM when you have just finished a heavy, relaxing meal, and that's a heck of a walk. You may need a cab, and the spend on cabs could eat up a lot of the savings you'll have gained from staying out there on the periphery.

I understand if it's about points. If that's so, go for it. If not, it might be better to try and stay in the city center.