One of my few advance bookings, Hotel Gallia was a nice, if over-priced hotel. It is decently located between the Colisseum and Termini station, which was the reason I chose it before I left the States. The staff was very helpful, even with me creating a key ring fiasco.
The rooftop terrace has a wonderful view of Santa Maria Maggiore and the breakfasts were very good, for Italian standards (i.e. a good choice of fruit, breads, coffes, and juices)
