We just got back from Crown Princess and hit most of your ports. Naples - we did Pompei on our own by taking the train - 20 minute walk from Port to the train and then 35 minutes on the train to Pompei Scavi. Did Pompei on our own with a map that they give you at the front entrance and our guidebook. Ephesus Kusadasi we took the ship tour. It was awesome - we had a great guide. I do not like to leave things to chance. Prefer ship excursions in busy cities like Kusadasi. When they drop you off at the rug place, just bow out - that is hit the market is right there across from the ship and the shopping is great. Livorno = you got to go to Florence to see David and the sights. Princess will make you take their shuttle to the end of the port = cost of $10 a person return and then you are free to either make your way to the train station to go to Florence or if you prefer do the ship tour. A couple of people missed the boat when they did it on their own. Lots of traffic. Rome - it is a hike into the city on the train - 1 hour but it is doable but depending on when ship arrives by the time you get to the most important site = the Vatican the hour will be late and the lines long. We spend five days in Rome before the cruise so we were able to see all the sights early in the am. Vatican can be done but with an expensive ship tour to get you in early. Otherwise, see the outside and take subway to the other important spots - colisseum, Spanish "Steps, Trevi Fountain. Monte Carlo - you can take Bus 1 or Bus 2 to the Casino. You can walk to the Royale Palace from the pier - Princess will tender you. Gorgeous city - beautiful views.
Venice - definitely St. Marks; Mykonos - 20 minute walk to the city along a road that is pretty narrow and no sidewalk Princess will provide a shuttle for $5 bucks a person return to the Yacht Club and then you walk a couple of minutes to town. Crazy town - you wil get lost but fun to meander - have a drink in little Venice and then go see windmills a few minutes away from little Venice. All the buses go to the beaches if you want to do a bit of sun bathing too. Have fun. If the Ruby Princess is anything like her sister, the Crown, you will be impressed. We are pretty fussy and we loved every moment on that ship and our med itinerary. Did not to to Instanbul. We did Athens, Corfu, Olympia, MonteCarlo, Naples, Mykonos, Venice Rome, Livorno.