Hi Skipper,
I have been to Rome 10 times in the last seven years and lived in Rome for three months a few years ago while I worked in the Vatican archives. In fact I lived not far from Via Firenze. The hotels along that strip are very tourist oriented, so your stay should be fine. But if you go to Rome again, I'll give you some better hotel hints.
First, do NOT hire a private car anywhere in Italy except Tuscany. Italian mass transit it excellent! You will be staying 2-3 blocks from the main rail station in Rome (Termini). Walk over there the night before you leave and use a kiosk to buy tickets (they take credit cards) for the train to Civitavecchia (I assume that is where you are boarding). The train is often faster than a car with all the traffic in Rome. It has been a few years since I have been to Civitavecchia, but I believe it only takes just over an hour to get there. When you buy your tickets (kiosk is in English by the way) check the times. Look at both departing and arrival times to make sure you do not get on the slow train that stops EVERYWHERE. The fast train only makes a couple stops, if any. If there is a Eurostar train going there, take it. For two, the trip should cost only 40-50 Euros at most one way. Oh, and don't take a cab from the airport to Rome. Too expensive. There is a very comfortable direct train from the airport to Termini.
I can give you some hints on what to see, where to eat, best gelato, etc. if you would like. I may also be of some help with ports of call around the Med.
Stephen