Peggy Lucero wrote:

>I'm attempting to start building a CD collection of classical greats.

Rethinking the question, I think my initial answer was a bit impulsive.
THe "all time" greats are of course not only found in the 20th century as
will undoubtedly made clear by other contributors to this list, who will
not hesitate to come forward with their awful Beethoven, instead of Bach or
Mozart or Schubert.  Back to "modern" music, what struck me after reading
your list again, is, that it only contains orchestral works.  The most
beautiful form of music however is chambermusic.  So your list should
include:

Shostakovich: pianotrio nr 2 & pianoquintet, and all the stringquartets (nr
8!!), and his cello, violin and viola sonatas.
Nielsen: wind quintet
Hindemith: Kammermusiken and harpsonata
Korngold: stringquartets (nr 2!) and Suite for strings and piano left hand
Prokofieff: violin sonatas
Janacek: string quartets and violinsonata
Pijper: string quartets
Khatchaturian: trio for violin, clarinet and piano
Milhaud: suite for violin, clarinet and piano (a good starter!), string
quartets
Ravel & Debussy: string quartets and violin sonatas
Debussy, cellosonata
Poulenc: trio for hobo, bassoon and piano, clarinet sonata
And last but not least:
Bartok,: contrasts for violin, klarinet and piano, and the 6 stringquartets,
and the pieces for violin and piano, suite for two piano's and percussion
If you want something out of the way, try:
Arutiunian: trio for violin, clarinet and piano

All those works are available oc CD, the Arutiunian might be difficult to
find however.  I wish you many exciting hours of listening

Peter Wisse,
The Hague Holland