It is very hard to provide a list without having initial reactions to some specific work, but here's a list, on the top of my head as I am typing, of a few works that would fit your criteria while being diverse enough that you can later "dig deeper" in the genre (I will try to be very wide):
1) Zoltan Kodaly's sonata pour solo cello opus 8 (if you have the M80, this is a must to impress visitors!)
2) Middle or late period string quartets by Beethoven (ideally played by Quartetto Italiano)
3) Highlights from any of Mozart's greater operas (Don Giovanni, Le nozze di Figaro, Die Zauberflote...)
4) French suites by Bach (played on cemballo, ideally with Gustav Leonhardt or Tom Koopman)
5) Concerti by Vivaldi
6) La Mer and other orchestral work by Debussy
7) Shostakovitch symphonies
8) Pulcinella or Rite of Spring from Stravinsky (if the latter, try to get it with Pierre Boulez as conductor)
9) El Amor Brujo from Manual de Falla (ideally the 1915 version, but they are all good)
10) Schubert's Impromptus for piano or his Moments Musicaux
There it is. Not very scientific, but an actual "must have" list, would take me more time than I can steel from the company!
But I think you would get a good sense of what you like and don't like with these.
