Patrizia’s place is the best accommodation you can get at an excellent ratio price/quality for visiting Vatican city. Vatican Corner is 2-3 bus stations or 15 minutes walk from San Pietro Basilica and 20 more minutes from there to Musei Vaticani. The 916 bus takes you directly to Piazza Venezia in 20-25 minutes, but I suggest you to use the metropolitan MA from Ottaviano station instead to reach the downtown.