Do sorrento and pompeii from naples/livorno (cant remember which one is which) florence and pisa is a really good trip too. Do rome on your own as its fairly easy if you catch the train from civitavecchia where you dock and its really cheap. Monaco is worth doing on your own - again just catch the train - really easy to do. Just remember when you take the train back leave enough time to catch the next one just in case so you dont miss the ship. Have a good holiday.
Why not do your own research and DIY - it is much more satisfactory than being herded around. Try going to boards dot cruisecritic dot com and scrolling down to the section called Ports of Call and clicking on the link for Europe.
That is a good idea professorplum but when you go to the more historic places like pompeii they give you information that makes it so much more interesting than doing it yourself - i do agree with you but its not always the best option to DIY.