I really enjoyed my stay at Frank & Soledad's place. It was incredibly clean and well-run. They don't live here, so the feel is closer to a hotel than to staying in someone's house. The room is not right in the city center but it's within walking distance of most things that you'd want to do - 10 minutes to the train station, 15 minutes to the Colosseum, 30 minutes to the Pantheon. I'd definitely stay here again.