We stayed in the IQ Hotel Roma, Via Firenze, 8, not too far from the central train station, last May. I highly recommend it, but it is not cheap. We paid 214 euros per night, and breakfast was another 10 euros pp. They might give you a better deal, if you stay 3 nights, or longer. I spent a lot of time researching hotels in Rome, before we left, and this was the best deal. We spent one night in Rome, before flying home, at the Hilton airport hotel - very nice, but it is at the airport. The airport Hilton runs a free shuttle bus in town several times a day, but it can take an hour each way, if traffic is bad.

When we were in Rome in 2007, we stayed at the then recently opened Hotel Diocleziano, which is less than 2 blocks from the Termini Station - but their rates are now higher than the IQ hotel. Rome is wonderful - but expensive. Good luck.