Hotel Dorica has everything that can make a stay in Rome comfortable. The owner, Peter, is friendly, helpful and efficient. He understands the off-season. The hotel offers great rates at the moment. A double room for 75 Euro a night is a steal. Rooms 23 and 24 share a small courtyard at the back and are ideal for smokers. The rooms have double-paned windows and so even the street-facing rooms are quiet. The decor may be generic, but the rooms are more spacious than an average room in Europe (where sometimes there's room for one suitcase at best, apart from the guest). The bathrooms look new. Apart from minor things like body lotion, I can't think of anything that was missing.
Peter, originally from Ancona on the eastern coast of Italy, has visited NY and SF several times. He's worldly-wise and funny. He and his daughter, Emmanuella, run a very efficient hotel. The breakfast is good, although not elaborate, but the service ensures you have a good start to your morning. There's an alternative in the Gran Caffe Piacente, next door, which opens at 6 a.m. You could also go there for a drink in the evening - munchies are free.
Most sightseeing spots are walkable from Piazza Viminale. You may need to take the metro to go to the Vatican, and there are two Metro stations - Repubblica and Termini - that are close to Viminale. A cab ride to, say Piazza Navona, costs single-digit euros. Another plus is that the shops in this area are not tourist-traps.
Dorica concentrates on the basics and gets them right. Therefore, it is very good value, one of the best I've seen in Europe.