We stayed at the 3 bedroom apartment in Trastevere. It was large and was on the corner overlooking the Ponte Siste foot bridge. There were 9 windows overlooking all the action and the location was fantastic.
The downside was that the action continued well into the night! If noise bothers you while you sleep I would bring some earplugs.
In spite of the noise I loved the apartment and would consider renting it again. The apartment is actually nicer than the pictures!