Here are some thoughts regarding our trip...
We booked a private driver to pick us up in Rome. After flying from Western Canada, we were thrilled to have someone meet us and take us directly to our hotel. Great relief. We used ROMACLICK.com - the transfer to our hotel was $48 Euro for two people.
The next day we booked the same company for our trip to Civitavecchia - we had the driver pick us up at our hotel at 2 pm therefore allowing us extra time to tour Rome. This cost $130 Euros, well worth it - it took the driver only 40 minutes from inner city Rome to the Port.
Accomodation on Land:
In Rome we stayed in the Bettoja Hotel Nord Nuova Roma - very nice clean hotel close to the train station so we could take all of the tour busses on our own without having to buy a package tour.
In Venice, we stayed on for three days at the Arlecchino Hotel. I had booked this on Expedia and had no idea where it was. When you get off Princess, we were bussed to Piazzale Roma (only a 5 minute drive from where the ship docked) - we couldn't believe our eyes when we got off the bus, looked over the bridge and there was our hotel. Fantastic location for proximity to the train, vaparetta's (water busses), restaurants. Not as expenive as staying right on the canal or near Piazza San Marco. However, you are only 10 minutes away by water bus.
We found the vaparetta's an excellent way to get around. We bought a 48 hour pass for $20 EURO per person and rode all around for the two days. At first we got on the longest route so we could sightsee. We went to Marano & Barano Islands - on and off as much as you like. Barano Island was our favourite, very quaint with fantastic prices and different things than we say in the main markets.