We stayed at Rio Hotel for several nights, and our stay was very pleasant. The hotel staff are friendly, and the staff member who checked us in also helped take one of the suitcases up to our room. There is no elevator, so keep in mind that you will have to transport everything you have up at least one flight of stairs. That said, having a third story view on the little square outside the hotel was great. Our 18-month daughter loved to people watch from the window as we prepared for the day.
The rooms were updated and clean. And one the best conveniences of this hotel is its proximity to San Marco. During a chilly January week, this hotel was warm, and aside from the lack of an elevator (which is understandable given the age of the buildings) we had a wonderful stay.