Sade I first heard considered a smooth jazz singer on Cool TV in 2004. This makes sense... I could never quite place her musical style.
Frank Sinatra was more of a surprise. I thought he was more of a contemporary crooner. Then I learned he recorded an album with Duke Ellington as well as tunes with other artists. He too gets major airplay on Cool TV, though initially I thought he just fit the 'cool' part of the name.