With Guido's apartment you will find a comfortable clean place about 600meters from the coliseum. Within the area there are restaurants and bars. Guido is a good host with good communication when needed. You will need to pay for parking on the street. But I wouldn't recommend a car in Rome. There is no need. We did allot of walking whilst there as the main tourist area is the other side of town at the tivoli fountain. You could probably get a train there easy and there is one not far from Guido's.
I think his prices are reasonable for the area too so over all we had a good experience and would stay again one thing do is that it's up 3 flights of stairs which literally feel like 5. So if your older I would take account of the track up to the apartment.