My sense about Ellington is that his composition and arranging efforts were
actually primarily focused on his sidemen.  He stated on several occasions
that his output was created especically to the individual strengths (sound
and improvisational styles) of his soloing musicians, especially Harry
Carney, Bubba Miley (in the very early days), Cat Anderson and his unique
trombone choir comprised of Tizol, Jackson and Woodman.  The only musicians
he gave free reign and didn't arrange for were rhythm players who were on
a reasonably tight string supporting the soloists in the band.

As the years grind by I believe Ellington continues to evolve into the
definitive musician/creater of a great "classical" musical art unique to
American civilization.  I believe few of us have heard the complete catalog
of reportedly over 2500 compositions he left as a legacy.  I don't believe
a complete collection exists in any one place (or even in several
locations) in the form of manuscripts or recordings.  If not this is
surely a worthwhile task to be undertaken.

Bernie Gregoire
Hingham, MA