On the vocal jazz issue: It's not just women that prefer vocal jazz. A great singer is a gateway into making any kind of music accessible, inviting people into a song on a level that everyone can understand.
We all strive to be great players with unique voices. But in my opinion, a "good" singer speaks much more directly to an average person that a "good" instrumentalist because the listener is given a way to relate to the music that does not rely as much on abstraction. Once they have begun to relate to the music on that extra lyrical/story level, they are more likely to appreciate the abstraction that follows.
I agree with the above if you substitute "any" for "great" and "good" singers. People, men and women, relate more quickly to words--period. How many times have you heard: " I can't hear the melody?
Learning to "hear" jazz is like learning another language.
Chris,
I agree with most of what you wrote, but my intent was not to discuss the quality of jazz vocalists. I belong to the Lester Young school of silently "singing" the lyrics of a tune (if there are any) as I'm playing it. (I also sing on gigs when I have to

However, I stand by my opinion that women players are more drawn towards vocal jazz than instrumental.
During the 60's and 70's in NYC, I always kidded with my wife, Judy Lincoln, also a vocalist, that the chick piano players in this town treat me like a towel in the way they pass me around. Much of my career was backing female singers (there were males too. Bobby Cole and Reg Wilson for example) in a piano trio setting. I think part of my success with the gals was that the word got out that I was dependable and wouldn't try to nail them.
The following is a quick list that comes to mind:
Karen Springer
Suzanne Forham
Daryl Sherman
Nina Sheldon (backing Johnny Hartman)
Jane Getz (AA Friday night get togethers in a village church basement)
Joanne Brackeen (same AA gig)
Many more that I forget.
All of these ladies except Joanne and Jane were vocalists; it's what got them the work, and they loved doing it.
Jane was kind of quiet, shy even, but Joanne was a dynamo. She had so many ideas that she tripped over them. Her mind seemed to be going much faster than her hands. I was so happy when I heard she got it all together with the Getz gig.
Straying here. Sorry.
One more thing, jazz in the olden days was a rough often brutal life. One nighters very far apart, lousy hotel rooms and lousy food. A lot of boozing. Always feeling sweaty and grimy. And most of all --dangerous. Think Doug Watkins, Clifford and Ritchie and of course Scotty. It wasn't very appealing to most women. Hell, it wasn't appealing to me.[/QUOTE]