Not sure where we are with the division/classification of things, but IMHO Gilbert & Sullivan belong with stage musicals, not opera.
Fledermaus and *The Merry Widow * definitely belong. Regardless of their opera/operetta classification, they are part of the mainstream opera culture.
The G&S have been embraced more by Musical Theater culture than by the opera world, so they probably belong on a MT list instead. But that’s debatable…
Mozart’s *The Magic Flute * was a big omission from my last list, by the way. (but I see it’s already been mentioned), as was Carl Maria von Weber’s Die Freischütz.
ROFL!
Um, as to everyone else, the key word should be “essential.” It isn’t “essential” if it includes everything written in the way of opera during the eighteenth and nineteenth centuries.
Lakme - Delibes.
In fact there are many other parts of *Carmina Burana * that are much better than O Fortuna, such as Ecce Gratum, Were diu werlt alle min, In taberna, Veni venias.
The whole thing? Or just the duet Au fond du temple? I know people who have heard and loved the duet, rushed out and bought a recording of the full opera, and then been sadly disappointed with the rest.
The duet is my favorite part, but I wouldn’t say I’m disappointed by the rest. I’m not a big fan of opera to begin with. I morsel them.
As someone who has performed G&S for over ten years, I must respectfully disagree. The collaborations of Gilbert and Sullivan are every bit as worthy as many other works that reside quite comfortably in the operatic canon.
I have heard many express the opinion that G&S is not opera. Part of the reason that this opinion holds sway is that the D’Oyly Carte Opera Company held an exclusive monopoloy on professional productions for nearly a hundred years. Therefore, while the world of opera was establishing its standards and preferences, the only productions of The Pirates of Penzance or Patience that most people ever saw were from amateur companies. So even though the monopoloy no longer holds, most people in operatic circles regard G&S as only worthy of amateurs. The Metropolitan Opera of NY, for example, has never performed a single production of a G&S opera. The NY Philharmonic actually played a piece composed by Sullivan this past year – something that had never happened before. So at least some have awakened to the startling realization that G&S, while not, perhaps, as clever as Mozart or as tuneful as Strauss, are worthy to be in the same classification.
A strong second or third for Puccini’s Tosca. A beautiful aria for the soprano, two arias for the tenor, and a duet. It don’t get better than that. 
I like Shaw’s recording of Verdi’s Requiem.
For lieder, may I suggest **Strauss’ ** Four Last Songs? I highly recommend this recording with Gundula Janowicz as soloist.
Randall Thompson, The Last Words of David and Alleluia.
Will there be one for Classical Choral?
No. Any choral music you want to list will fit in here, in Classical, or in Contemporary Classical (coming soon).
I’m not sure that if fits here, but it is choral music. Hildegard of Bingen’s “A Feather on the Breath of God” the Gothic Voices recording with Emma Kirby http://www.hyperion-records.co.uk/details/66039.asp
is sublime music.
So Comtemp Class it is…
Didn’t suggest it earlier since I didn’t know where to put it, but since nobody seems to have suggested it anywhere the two Stabat Maters by Pergolesi and Vivaldi. Because they’re both excellent, and because Vivaldi deserves to be remembered for something other than the Four Seasons.
Arvo Part, Te Deum
Padilla, Ego Flos Campi mass
Any men’s chorus work from Georgian Republic, e.g. that of the Rustavi Choir
I was thinking that, if you wanted to get a newbie into choral music, it would be a really effective hook to play that song that they’ve heard in this commercial and that commercial, this movie and that movie. I approached the question as if I were assembling a CD for sale.
Oh, there’s endless CDs on the market using this ploy. The trouble is, this doesn’t work as a hook. They’ll include O Fortuna, but not the rest of Carmina Burana (which would take up half a CD by itself).
As **GorillaMan ** notes, there’s already a huge market for compilation “Best of” CDs.
Every now and again our choir does concerts where the program consists solely of the well-known “hummable” bits of choral music that people know from television advertisements, films etc. The idea of course is to get the audience interested enough to come back later to hear some more challenging works. Interestingly enough the most successful concerts we’ve done in recent years from this point of view (i.e. attracting non-musical punters) have been the performances of *The Lord of the Rings * Symphony. They came in their millions for that and I gather that we picked up quite a few new subscribers as a result.