Marina & Francesca have an amazing flat in the Garbatella district, clean and sizeable enough for a number of people. It's very close to the Garbatella Metro station, less than a 5 minute walk, allowing for easy access to all of Rome.
If you're a fresh tourist to Europe/Italy you may have some trouble in the district as it isn't tourist heavy, but, it's very quiet, calm and we highly recommend it. Close grocery stores and shops make it even easier!