A nice neighborhood of Testacho is a little bit far from the city centre (e.g. Pantheon...) though it's defenitely worth a stay. Actually, it is possible to explore Rome on foot from there but it'll take more time. Sergio is a nice guy. The room is kinda old-fashioned though still pretty cozy and neat. There are a lot of guides and maps in the room - very useful.
They smoke in the house.