If you are looking for a great hip spot to stay, with lots of room , then I strongly suggest Rosa's place. We have 2 teenagers, so the apartment with the loft upstairs with double beds for the kids is ideal! The other bedroom upstairs in the other bedroom was great for us, but if you have any mobility issues, are overweight or get up many times overnight to use the washrooms, this is not for you since you can acess the bedroom only via a small winding staircase.
The location is in a very hip place with plenty of cafes and restaurants nearby and you are also within walking distance of most Roman sights. We walked everywhere! I highly recommend this apartment, and oh yes, even though there are lots of pedestrian traffic during the day, the apartment is an oasis of quiet. Thank tou Rosa!