From my understanding, I can book tickets for the Vatican Museums and Sistine Chapel online at Vatican.va, which also allows you to skip the line.
What about St. Peter's Basilica? I know it doesn't cost to get in, but does the "skip the line" part of the ticket include entrance into St. Peter's or do we have to enter it separately?
I am trying to avoid standing in the line for St. Peter's because we have no choice but to go on a Monday, which from what I have read, is a busy day.