I love Sinatra. Sometimes, I think George Jones is the closest thing to that sort of mastery as a stylist.
My understanding is that a lot of the classic Reprise material was recorded on a three-track. In essence, two tracks to get the music in stereo and one-track for Sinatra's vocal. I seem to recall a description of this in George Martin's "All You Need is Ears."
Steve,
Mojo Pie