My family stayed for a night at Marina's place, which is very conveniently located a short walk from St. Peter's and from a bus/train station. The neighborhood is safe and we parked our rented car on the street for free.
The apartment is small but has all the amenities needed and is clean and nicely decorated. Marina is one of the nicest and most welcoming hosts that I've met through my Airnb stays. She gave us all the tips we needed for our short visit to Rome and Vatican; an outstanding host!