I just returned from 12 days in Rome, staying at the Hotel Portoghesi. It was terrific. The hotel is small and pleasant, and the staff were warm, friendly and helpful. The breakfast exceeded my expectations, with a variety of proteins in addition to the usual bread, fruit, cereal and yogurt. The location cannot be beat. A two minute walk to the Piazza Navona, five minutes to the Pantheon ... easy walking distance to most major sites. Best of all, it is immediately next to a small but absolutely gorgeous church, San' Antonio dei Portoghesi. I stopped by this church several times when the organist was practicing, and also heard two (free) organ recitals. It was stupendous ... more impressive than Saint Sulpice in Paris, in my opinion.
The only caveat is that there is significant street noise at night. This was not a problem for me, and I suspect you will get street noise at most hotels in central Rome. But if you are sensitive to noise, you might take this into consideration.
I personally loved this hotel, and I give it an enthusiastic recommendation.