What tracks offer the best left right separation?


Separation is a big part of a live performance. Name your medium streaming, turntable you name it but the key. Is the track you listen to and the separation you get. 
128x128chrishood1
There were recordings of trains going from one side to another back in the old days.  Try one of them, maybe.

Cheers!
What is and What Should Never be from LZ II has a pretty good channel separation break in the middle of the song. I only listen to analogue, either R2R or Vinyl and it sounds great on either. 
Some of the early Beatles records had singing in one channel, music in the other. Now, that was separation!
I've got a bunch of the old "bachelor pad" aka "space music" collections from the 60s; many of them feature hard-panned instruments.  Has nothing to do with live sound, but was fun for the pipe-smoking sophisticat trying to bed a sweet young thing by impressing her with the size of his "hifi".