For business - The Giulio Cesare, Rome. Finding a good business hotel is like selecting an airline - functionality and convenience are prime considerations.
And I like places with a gym or a pool, because I reckon I've spent 50% of my time on planes over the past couple of years and it gets brutal if you don't work out. The Giulio Cesare is great - it's close to Rome's business district, and it has good internet connections in every room. It is popular with international travellers, so you can read newspapers from any part of the world over breakfast. The staff have a sense of urgency, which is unusual in Rome, and they can get you a taxi anywhere within three minutes. It's not that spacious, but it is comfortable and relaxed.