Arrivé à couple days early, and stay a couple days after, if you can. It’s been many years since I took this tour so St. Peter’s and the Vatican etc. were included, but I felt I wanted a lot more time as the place was quite crowded. If I were to go again, I would want to book a very early, or very late time in an attempt to avoid some of the crowds. I also went out to Ostia Antica on my own, after the tour, and went for a long walk down the Appian Way, and popped into some sights there. In Venice, the tour goes to Burano, but not Murano, so I did that pre tour, plus spent some time riding the vaporetto down the grand canal as the tour doesn’t do that either. There was time during the tour to visit the Doge’s Palace so some of us went in later in the day when there was no line up to get in. In Florence the time options are limited, but some of us managed to climb the Duomo.