I listened to a
lot of Norah Jones in Iraq (Enya too, helped me sleep), and I still love her voice. Feist is off and on, but she has some great stuff. I have a live version of "Honey Honey" that's amazing.
I tend to go for more of a smoky voice in my girl vox:
Elizabeth Fraser, Skye Edwards, that girl from Portishead (Beth something) etc. Although Sarah Brightman is amazingly talented (La Luna is a favorite).