Winter is a great time to visit Mediterranean ports. Ships and sights are much, much less crowded and temperatures are comfortably cool, although some rain may fall on excursion parades. An umbrella and and rain jacket are good trades for standing in long lines in sweltering heat. The sights and sites are the same.
Ports of call offering access to Rome, Florence, Pisa, Monte Carlo, Nice, Aux en Provence, Barcelona, Valencia, Sardinia, Sicily, Naples, Pompeii and the Amalfi Coast are a good sampling of the Western Med and its cultures and cuisines. Getting to ship from Rome Airport (FCO) can be adventurous, so we opted for a transfer from the cruise line, which was more expensive but offered certainty for a tight connection. Port shore excursions from the ship likewise tend to be more costly, but offer from-the-gangplank convenience. Take a look at hop-on and hop-off city bus tours where available or form your own small tour group and either book with a local provider in advance or upon arrival. In many ports, shuttles are available from the ship to city entrance a little or no cost.
For those planning self-drive tours before or after their cruise, Civitaveccia, the port that serves Rome, has car rental agencies to accommodate leaving for Tuscany or other area of interest without the hassle of Rome traffic and returning the car to FCO airport. Consider including a GPS rental with the car (or bringing your own) and choose a smaller, rather than larger, auto for ease of maneuvering and parking on driving excursions.