For people who don't need to be in the absolute thick of things, Roberto's place is perfect. The apartment is beautiful, and the terraces a fantastic bonus in a hot city. I was traveling with my (somewhat elderly) parents and location was perfect for us. Not crowded, but in walking distance of the lovely neighbourhood Testaccio where we did most of our eating and shopping. To go to the centre, the tram along Viale di Trastevere is very convenient, only sometimes extremely crowded. Only downside I can think of was the traffic, which is noisy and runs from quite early till quite late. But I think it's hard anywhere in Rome to find a quiet spot.
Roberto is the perfect host, very welcoming and kind, and very much around and reachable if necessary.