mahgister, thanks for the music!
stuartk, I have a lot of Ella Fitzgerald, Sarah Vaughn, and Billie Holiday albums. They often don't improvise except in the way they interpret songs, like Frank Sinatra. No doubt, Fitzergerald can scat with the best of them, but she doesn't always feel the need. So, I don't think improvisation is a necessary attribute of jazz. BTW, I think you didn't like Tania Maria, but she can scat like nobody's business.