David Stewart asked for cd recommendations of Mozart works he does not own;
he even listed the works he does own.  That does make it easier to respond.

There are no string quartets/quintets on David's list.  Recommend the Haydn
string quartets and Mozart's later quartets as well.  Check out the Salomon
on Hyperion for the quartets and the quintets.

Do you have something against chamber works with clarinet? Try the
Mosaiques on Astree for the clarinet quintet.

Some of the piano concertos are missing; every one from no.  6 up is a
must.  Bilson, Schiff, Moravec, and Barenboim are some good ones.

No piano sonatas? Uchida's the best in my opinion.

You need more operas - Cosi, Don Giovanni, and Magic Flute at a minimum.
Try Klemperer for the Magic Flute, Ostman for Don Giovanni, and Mackerras
for Cosi.

I've just provided a very small number of recommendations considering the
huge discography involved.  More insight into David's preferred styles
would help narrow things down.

Don Satz