Testaccio is nice district in 20-30 min walk from historical centre. There are several supermarkets, fresh food market, Italian restaurants. Also 20-30 min walk from Ostiense railway station (to/from airport), Pyramid metro station (to/from city centre).
Giovanni’s apartment is love. You’ll find comfortable studio, superview from balcony (city centre and mountains), everything what do you need.
Host was super friendly man! Highly recommend.