Virginia's "Loft" is an excellent place to stay in Rome. We walked EVERYWHERE, only used the train to get into the city from the airport. That's why we found it slightly tricky to find...wandering about at 10pm at night with only a paper map was perhaps not sensible!! The Loft is in a quiet back street, but close to everything you'd want to do in Rome.
The apartment is lovely, with separate areas for everything (you don't have to sleep or make a drink in the lounge area!).
No disturbance from the street or apartments above/next door. Excellent wifi. Lovely shower. Virginia was very friendly and responsive. I would absolutely recommend this place.