I have to be honest and say I have struggled to get much out of Zemlinsky so far, and have not really persevered either. Mein Schlecht, alas. I felt conned when I was told the Lyric Symphony was "another Lied von der Erde", and it frankly isn't.
I have enjoyed some composers who might be considered similar to AZ, like Diepenbrock, Schmidt and Schreker, perhaps I ought to have another go, and I have several discs from James Conlon, rate him pretty highly, so he may be a good way in? Any pieces other than the Lyric you'd say you've particularly liked, the two other Symphonies aside?