Modern day female jazz recommendations

Gretchen Parlato
Melody Gardot

Marilyn Scott is a longtime favorite female jazz vocalist of mine.

Marilyn Scott Discography

Rachael Price. In my opinion, by far one of the best female jazz singers currently recording. Her rendition of "You Go to My Head" makes me weak in the knees. The sultriness of her voice is incredibly sexy and enticing. That's what singing jazz is all about to me.

http://www.youtube.com/watch?v=l_WzB3l66o8

Diane Schuur....any of her albums, especially the GRP ones (Grusin Rosen Production) are fantastically-recorded.
Her vocals are natural, unforced, and so realistically recorded, and her songs are wonderful to listen to. Wonderful orchestra backing that's exceptionally well-recorded.

You must try "New York".

There is an NPR issue CD called "Modern Jazz Divas" that I bought for some new exposure in this area and is worth a listen