We have had a very pleasant stay at Cristina's flat. It is a very comfortable and very well located, nicely decorated and close to metro, shops, Vatican etc....
We could go everywhere by foot also.
The flat is spacy enough for a family of 5 with teens.
You have to be aware that you have to pay touristic taxes on top of the price : 3,5€/ person and per day.
We definitely recommend this place, as well as the nice restaurant just the other side of the road : a new restaurant call Felizeterie : great inventive cuisine !