"The least fatiguing "; Why does she affect me in that same fashion? It's because she plays the music and not the notes, she plays the music in between the notes. An example of that is on "Mack The Knife"; I've heard this song a zillion times, but never have I heard it sound so "musical" as when Mary Lou Williams played it; it was musical with a jazz foundation.
Mary lou was a natural born musician; her mother would not let a music teacher get close to her daughter, said it would ruin her natural ability; she learned how to play by playing. As a child she played "chitlin struts" (never been to one) and rent parties. Every time she strikes a key, the sound rings out "Mary Lou Williams", her individuality is just that unique.
Rok, I bet right now, you're having a hard time stopping to do anything else but listening to the CD's you recently acquired by Mary Lou; that's what I meant by going to "Mary Lou Ville", now you don't want to leave.
Enjoy the music.