Myself and my son spent 3 days in one of the garden suites at Sentho Roma and had the best city break in Rome we could have hoped for. The suite is spacious - two double beds in a large partitioned room - with a galley style kitchen diner and 'chillout' snug, which he loved. The staff are all lovely, the welcome is friendly and relaxed rather than stuffy and superior, and nothing is too much trouble for them to organise.
Of course, one of the best things for us was the location: the street is pretty quiet, ideal, and less than a 10 minute walk from the main railway terminal; a 15 minute walk to the Colosseum and Forum; 20 minutes to the Capitolini Museum; 20 minutes to Trevi; 20 minutes to Spanish steps and its high end shopping area. We walked everywhere because central Rome is compact, and the best way to see it is to potter around in the morning and evening - afternoons can be very hot. Well worth doing is a half day cycle tour that takes in the Appian Way and Park of the Aquaducts, a highlight of our city break.
I don't think either my son or myself would even consider staying anywhere else than the Sentho Roma the next time we make it to Rome.