The Merchant of Venice) or shows I've been told I would have adored (thus, from many years ago, A Delicate Balance). As a historian, I wish like hell, all the time, that I had had the chance to see just about every musical that I have researched, reconstructed, and written about, but that ran before I was born, or before I was old enough to see them: every single rock musical to run in New York before, say, the late 80s; every adult musical to open in New York through the 1970s.
But really, on a personal level, the show I most regret not having had the chance to see was Carrie, which remains so near and dear to so many who got the chance to see it. By all accounts, Carrie was an absolute trainwreck that nevertheless had some moments of absolute brilliance; if you don't believe me, please read Ken Mandelbaum's wonderful description of the show in the intro to his aptly titled 1991 book Not Since Carrie: 40 Years of Broadway Musical Flops. I've sat through many a disastrous production in the past few decades of regular theatergoing (for example, see my review of the first incarnation of Spider-Man on this very blog), but something tells me that Carrie still remains the megaflop that has yet to be beat.
Someone I know who saw Carrie once made a quip about it that I will always remember, and that remains one of my favorite theater stories of all time. She said that she saw the show in previews, and that it was, indeed, truly, astoundingly, wonderfully awful. "Really?" I asked. "So, when the curtain call came, was the cast booed off the stage?" "Oh, no," my friend replied, with a beatific smile and a glaze in her eyes that still haunts me. "The show got a standing ovation the night I saw it. It was JUST THAT BAD."
Seriously, how could anything top that?