I noticed the artists you're listening to; they are superb vocalists, and at the same time, I'm recording those artists on my Technics reel to reel, plus I'm breaking in my new Grado Master cartridge.
"Grado" is the poor man's Koetsu, and that's exactly what it is. I've heard Koetsu many times; when an acquaintance put Carmen McRae on, she came into the room through his Koetsu, that's just how fantastic it is.
You mentioned a source for records; I was just perusing the latest "Music Direct" catalogue and I noticed it has records of all the artists you mentioned: Sinatra, Nina Simone and Ella. It also has some of the records that others recommended. Since I'm the kind of guy who puts the music first, I can't help you on special records, but maybe some of those in the "Music Direct" catalogue will qualify.
Enjoy the music.