For the POB, I think it has changed quite a lot in the last two decades...
For example, "Etudes" used to be a "house specialty", as it was one of the most often performed works in the repertory (and also that version was created especially for the POB), but it was absent from the stage for almost a decade before being performed again this season, so the younger dancers are not so familiar with it (even though they did a good job), and neither is much of the audience. Lifar was the house specialty for decades, but the present direction seems to have decided to forget it completely

I guess that one can say that Nureyev's productions of "Swan Lake", "Romeo and Juliet", "The Nutcracker", "Don Quixote", "Cinderella" and "Sleeping beauty" have become POB specialties. And also, in the modern/crossover repertory, Preljocaj's "Le Parc", which has been performed over and over and over, especially during tours,
and Fortysthe's "In theMiddle, somewhat evelated".
Probably Lacotte's "La Sylphide" would be in that category, too.
Oh, and there also is, of course, the Défilé. Not really dancing, but they do it well, and the audience enjoys it !