We booked the Hotel Bernini Bristol Roma through Regent for a pre-cruise stay in October. It is convenient and the cost is reasonable considering breakfast and transfers were provided. We arranged our own air but we were met at the airport gate and escorted to a limo that delivered us to the hotel. The accommodations were very comfortable. We had balcony accommodations overlooking the piazza. Finally we had transfers to the ship. Total cost was within $50 of making our own arrangements and assuming the hassle and risk that goes with it.

The hotel itself is within walking distance of many sites of interest - Spanish Steps, Pantheon, Lamborghini Dealership, Ferrari Store, etc. You may want to consider an additional night since 2 days is simply not enough time to visit the major sites, let alone the other side of the river. The transfer between ship and hotel requires a half a day depending upon traffic and the skill of the driver.