Terrazza Pamphili is a lovely apartment featuring a stunning and huge roof top deck. We stayed here for 3 weeks this summer and had a wonderful time. The apartment is a 15 minute bus ride to the center of town and main sites but gives you a quiet oasis from the hustle and bustle of Rome. Dinner and lounging on the deck, drinking in the beautiful sunsets and 360 views can't be beat after a long day of sight seeing.
There is a lovely park across the street as well as plenty of shops and eateries in the local area as well.
Vatican City is walking distance (30 minutes) as is the Trastevere area (20 minutes) with its many restaurants, churches, piazzas and shops.
Lastly, as other reviewers have said, one of the great joys of this place is the host. Paola is a warm, kind and friendly person who makes you feel very welcome and goes out of her way to make your stay something special.