Don't know any particular hotel in Rome that matches your criteria. Hotel Abruzzi is a place which has a view over the Pantheon, but it sounds like you're after something more special. Anyway, Abruzzi is a nice place and in case you want to check it out here is their site:
http://www.hotelabruzzirome.com
Since you mentioned Sorrento, a great hotel there with really magnificent views is Grand Hotel President:
http://www.ghpresident.com/