Can't add a lot to a great list of vocalists here, but a minor suggestion, Jane Monheit has a lot of pedestrian stuff out there, but she seemed to find her strength in the "Surrender" album.
Gardot, Barber, Peyroux, etc. are all great ... might also look at Nancy Moore for interesting interpretations.
Gardot, Barber, Peyroux, etc. are all great ... might also look at Nancy Moore for interesting interpretations.