The double concerto, clarinet quintet, piano quintet, serenades, overtures,
deutsches requiem, Lieder, violin sonatas, viola sonatas, cello sonatas,
alto raphsody, piano music (sonatas, ballades etc), two sextets are all
quite listenable.

Anyway there's so much to explore in terms of different interpretations
already.  Furtwangler, Toscanini, Abendroth, Cantelli, Stokowski, Walter in
the symphonies (otheres will add more here).  Szigeti, Menuhin, Kreisler et
al in the violin concerto.  Lots to listen to, a lot of money to spend.  ;)

Derek