We had an amazing stay in Rome at Novecento apartments. We booked all three apartments for 16 people. There was all of the amenities that we could ever need, including robes and coffee machine. A five minute walk to the Spanish Steps. Within walking distance of The Trevi fountain and The Pantheon. Would highly recommend.
The only issue we had was with the transfer to the airport, organised through Novecento. It was a perfect journey from the airport to the apartment, 2 x vans for 8 people each. However, going home they were 40 minutes late, we ended up getting taxis from the taxi rank up the road.