I'm used to get a room at...
I'm used to get a room at Spring House Hotel, very close to the vatican city; it's cheap if you think it's in Rome and in a very nice zone (90 euros per room per night).
If you prefer to stay a little bit away from the crowd choose the Aurelia Holiday Inn: they've decent (not good, decent, ok ?) food if you're too tired for a restaurant; this is ideally suitable if you have a car.
Hotel Panama Garden: closest to Villa Borghese this hotel is not so bad but remember to ask for air conditioning, not all rooms are equipped with !!! (www.hotelpanamagarden.com/)
Pls remember: this is Rome ... prices are usually higher than the rest of Italy (excluding Milan of course ...)


