Location Location Location!
The Penthouse is minutes from the Metro and from there all the main sites are an easy 20-30mins by Metro and/or bus combination. You can actually walk to the Vatican if you are feeling energetic.
Seamless communication, easy transit and very nice apartment. Have an espresso on the terrace and a look out across the eternal city.
Highly, highly recommended.
Also the tiny bar just across from the primary school Rocks on Friday nights :)