Do get a tour guide for the Vatican - they can get you in without lines, and a good guide with an art history background will make it all come alive. We found one from some tourists we met in Florence and we made an appointment for a day with her. worth every cent! She did the Vatican, the Colosseum and the Forum with us and she was great company, too. I'd give you her name but it was 12 years ago and I've lost it.