Bernstein was a lousy conductor and a lousy composer. He even managed to make the Vienna Symphony sound bad. He was one of the earliest instances of the typical 60s celebrity: all fame and no talent.
West Side Story is the nearest he ever came to anything worth listening to, but even there he gives Shakespeare's story an immoral twist and grovels in political correctness.
Well, sorry, but I disagree whole heartedly with you regarding Bernstein.
West Side Story along with Sondheim's Sweeney Todd and Follies are arguably the finest musical's ever written. I also think his conducting of Mahler is definitive.
I would highly recommend his Norton lectures at Harvard called the "Unaswered Questioned" in which Bernstein argue his hypothesis that humanity is endowed with an inate musical grammar.
It is a dense 18 hours, but a very rewarding experience. It's available on DVD from Kulture.