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

Puccini wrote amazing stuff for the female voice.  His operas Tosca, La Boheme, and Madama Butterfly contain gorgeous writing for the female voice.  To my taste, his final opera Turandot is unsurpassed in this category, with two great soprano roles.  Try this:

I have enjoyed Italian singer, Laura Pausini. 

++1 Roberta Flack

Randy Crawford

Sarah Jarosz

Mary Fahl

Another +1 on Alison Krause

Emmy Lou Harris

Sheryl Crow's duets are very soulful

Permission in advance to laugh

Janis Joplin, listen to the song Try - she's all in

Patsy Cline, a true natural and sounds so effortless

Etta James

Whitney Houston

Aretha Franklin the original diva