Centro Storico puts you close to many of Rome's main sights and is ideal for exploring on foot, but stays are often more expensive and the area can be busy.
Monti combines a central location with local character, while Trastevere is a good choice for restaurants and lively evenings. Prati is generally quieter and convenient for the Vatican and metro.
Tip: Staying slightly outside the historic centre can offer better value. Check public transport connections, exact location and facilities such as air conditioning when comparing stays.