I would wholeheartedly recommend Costanza's apartment in Monti. The apartment was super-clean nicely minimal in its furnishing and decoration and very spacious even with two teenage children. Modern bathroom with a great shower, comfortable beds and functional kitchen. The rooftop terrace was a major selling point for us and did not disappoint; while it is a shared space we used it every day and always had it to ourselves, and the views were spectacular. Monti itself is a vibrant, culturally interesting suburb with great cafes, restaurants and independent fashion, jewellery stores and vintage clothing and interior design outlets, close to the ancient heart of the city (the Colosseum is literally at the end of one street; the imperial forum at the end of the other!). Costanza was super-helpful and accommodating, offering great local tips and arranging a private airport transfer. We would stay there again in a heartbeat.