I recently traveled to Naples for business and stayed at the Renaissance Naples in Italy. I highly recommend this hotel. I have stayed in many Marriott hotels around the world and found this to be a very pleasant hotel. Staff was courteous, rooms were sparkling clean and very quiet, and even the hotel gym was neat and tidy. The garage was a bit tight, since it's sized for tiny Italian cars, but this was the only issue we had in 4 nights accommodation. I look forward to staying here again, should my travels take me back to Naples.
I stay in Rome very frequently, and have thought occasionally about staying at the Marriott Naples, but I'd read negative reviews on tripadvisor and other review sites. Most of them seemed to have to do with the fact that the hotel was kind of old and the area around it was not particularly safe. Did you find that not to be the case? Because I'd love to stay there in the future in order to do excursions to the south.
We stayed there a little less than a year ago and really enjoyed our stay. It is located in central Naples near the port and we had a great view from our room. Breakfasts were served on the rooftop and were excellent. We wandered around the area to restaurants in the evening and to shopping areas without a problem. I would stay there again with no concerns. I agree with the comments of the original poster.