Looking for good recordings of female vocals I have not yet tried...

Roberta Flack, “The First Time Ever I Saw Your Face”, on the album Fist Take.   Simply breathtaking.

I might suggest Amanda McBroom. Has several albums on Sheffield, maybe other labels.  And also, just to perform the song she wrote, "The Rose," Bette Midler.

One of the most insanely badass albums I've been listening to lately is Cande y Paulo, it's mind blowing...  She is amazing... Honorable female vocal albums mention goes to London Grammar, Lake Street Dive, This is the Kit... All incredible female vocals that will change your life

And on the classical side, Get all four volumes of Wagner's Ring Cycle which features numerous very competent female vocalists.  Use the recordings of the Vienna Philharmonic under Solti.  They were recorded by Decca in the early 1960's if memory serves.  Available on vinyl and lesser quality on CD.  (no heat seeking missiles, I have both.)

Katie Melua 

+++1 for Eva Cassidy