If you go to royalcaribbean.com >before you board > shore excursions and select the shore excursions for your cruise it will detail what you see on this transfer.
I would recommend that if you wish to visit the Vatican and all the museums there and the Sistine Chapel that you go on a tour. They do get you to the front of the queues, which are immense in September, and will be far less tiring than a DIY effort. The rest of Rome can, with planning, be easily done on your own. ... Neil.