Beautiful island, we elected to just take a self tour with the hop on -hop off city tour double decker bus, and had an enjoyable time visiting the city on our own.
This was one of my favorite ports, and just a magnificent island with picturesque views. The tour to the cable cars was excellent, we the bus ride to the top of one of the islands was magnificent (and somewhat dangerous), with lots of winding roads!
Rome was not meant to be seen in a day, but the historic tour including Vatican City, Sistine Chapel, and St Peter's Basilica was outstanding. There is LOTS of walking, and of note, the lunch break is not until almost 2PM, so make sure you eat a hearty breakfast. The port is over an hour from Rome.
Genoa was a fun port, we did LOTS of shopping, which was only walking distance from the port. This was one of the biggest ports in all of Europe, so there is lots of commerce and small shops with good souvenirs at reasonable prices.