We will be in Rome from April 15 to April 23. Is there any day better than another to go to Vatican City? We are thinking Thursday, the 17th.
Which year? In 2014?
That week is going to be pretty busy at the Vatican. I can't think of a day being better than another. There will be tons of pilgrims in Rome that week.
April 17, 2014 is Holy Thursday (Washing of the feet by Pope)
April 18, 2014 is Good Friday
April 19, 2014 is Easter Eve - Midnight Easter mass
April 20, 2014 is Easter Sunday
April 21, 2014 is Angel's Monday.
The museums will be closed on April 20, 21, and the Basilica will probably have limited access. You need to book a tour or purchase tickets ASAP as the museum calendar is only showing tickets available on the 16th, the 17th should open up tomorrow for reservations.. Try Walks of Italy if you want to do a tour.