Chris Cornell's Euphoria Morning and Carry On albums demonstrate his rock-vocal beautifully. The first albums title track in particular is superb.
If you're not certain who I mean he's the ex-Soundgarden front-man who currently heads-up Audioslave. Maybe better know for You Know My Name, the title theme to the recent Bond, Casino Royale.
Other than that I've always admired Skunk Annasie's female lead, Skin. 100 Ways to be a Good Girl from Paranoia and Sunburnt still makes me take pause.
Admittedly both are rock vocalists and possibly not what you expected but you never know
Robert Plant and Alison Krauss on their album 'Raising Sand'. Their voices intertwine beautifully as though they really are singing for each other. So expressive.
Tim Buckley, his later work is more "jazzy," namely Happy/Sad, Lorca and to some extent Starsailor, but he has a lot more "edge" than the cats you mentioned.
John Martyn, Anthony & the Johnstons, Beth Orton, Beth Hirsch,Richard Thompson and the unbelievable Tom Waits! Some of these are an aquired taste mind you. You tube 'Gods Away on Business' by Waits. Superb.
This one will depend if you're into his sort of stuff, but David Sylvian's solo albums (ex Japan), especially the more recent ones (Dead Bees On A Cake for example), are very well recorded, and his vocals usually sound amazing.
Bonny Prince Billy, William Fitsimmonds, joshua Radin and Shawn Mullins on the male front, Melody Gardot and Beth Rowley have fine vocals.
If you like Blues David Johansen (and the Harry Smiths) a Chesky Recording which sounds Fantastic.
And For something a little different try Isobel Campbell & Mark Lanegan they have 2 Albums out, I have Sunday at Devil Dirt he certinally has an origional voice.
Bonny Prince Billy, William Fitsimmonds, joshua Radin and Shawn Mullins on the male front, Melody Gardot and Beth Rowley have fine vocals.
If you like Blues David Johansen (and the Harry Smiths) a Chesky Recording which sounds Fantastic.
And For something a little different try Isobel Campbell & Mark Lanegan they have 2 Albums out, I have Sunday at Devil Dirt he certinally has an origional voice.
if you enjoy blues, listen to Guy Davis on the albumn called 'chocolate to the bone'
Linda Ronstadt's album recorded 2 or 3 years ago along with Cajun singer Ann Savoy "Adieu False Heart" is truly a work of beauty with the bare simple arrangements allowing the voices to really shine.
Tom Waits is wonderful, but from your spec then Joni Mitchell in her jazzy phase - (Hejira and Hissing of Summer Lawns are fine examples) should go down well. Tori Amos also has a fine voice and plays a mean piano.