In the last year I've become much more acquainted with Superman as a character, coming out of my life mainly being a fan through the DCAU. I've read Kingdom Come, Superman Unchained, DOS, Man of Tomorrow, Last Son of Krypton, his New 52 solo series, 50 issues of the Byrne Superman run (Was confused mainly because I didn't follow Adventures of Superman/Action comics), the anthology 2006 series (Adventures of Superman), and his issues in Rebirth. I'd like to think I have most of my bases covered regarding his character, minus AllStar Superman, Red Son, and some of the others.
What are some of his lesser known stories/arcs that should be checked out mainly pre-Crisis that would shed some more light on his character prior to the new 52? What do you recommend someone who is versed in the character but should check out for an added layer of knowledge to this iconic character. I was going to start Superman: The Man of Steel (1991-2003), but was curious if there is something I should read before binge reading another massive run.