We had a wonderful time in Rome at Federico's apartment. It's small but very cosy and you got everything you need. Best thing about it is its location, just a five minute walk to the Colosseo and the metro station. Also the center can be arrived by foot.
Federico was very friendly and helpful, although we didn't meet him personally. He always responds very quickly and left us a map with very very good recommendations where to go to eat (you really have to try the tiramisu at Luzzi's, it's amazing).
All in all, we just spent great four days in Rome!