My wife and I honeymooned it Italy in 2005 and stayed at 2 Marriott properties while in the Rome area. We stayed 2 nights at the Rome Marriott (Grand Hotel Flora). This hotel was absolutely beautiful and maintained the charm of Italy. It's location was walking distance to many key spots in Rome and also close to the metro train. I would highly recommend this property.
The other property that we stayed at was the Courtyard hotel near the airport. We had an early morning flight, and wanted to stay very close to the airport. This hotel was extremely simple and generic, but fit our needs. It's a bit hard to get to though. You have pay for the hotel shuttle to and from the airport (5 miles away) which we found odd, as in US hotels this service would have been complementary.