[BluesDuke]

all Mahler really wanted in life was to be Richard Wagner......Is that too much to ask for a composer?

Yes.

[BluesDuke]

Another entry for the list, in case no one else has plugged it in yet:

Richard Strauss, Also Sprach Zarathustra (the full composition, not just the famed overture from you know what film...)

And...

Gyorgy Ligeti, Requiem for Soprano, Mezzo Soprano, Two Mixed Choirs, and Orchestra and Adventures. (I have recordings of the complete scores of each piece, not just the edits used in 2001: A Space Odyssey. Ligeti is perhaps one of the most underrated of the 20th Century classical avant garde...)