Good morning, Bruce! Hope you're feeling better soon.
For pure entertainment musical, I'd have to go with the much-reviled revival of "On The Town" in Central Park, as much because of the circumstances of the day as the show itself. I was in a miserable part-time job, and was becoming disenchanted with my graduate school program. I was accompanied by a dear friend's dear friend, a striking tall Irish lass who willingly became my "arm candy" for that summer. It was a perfect evening. We had sushi at a kosher place that closed down far too quickly (I had a great rapport with the sushi chef; when I came in, he'd ask how much I wanted to spend that day, and prepare what he thought was the best of the day). Walking into the Delacorte, and seeing the bridge set lit up against the backdrop of Central Park, we both just said "wow." I wasn't at all familiar with the score before, and Bernstein's opening notes had me jumping out of my seat. Lea DeLaria, Mary Testa, and company were absolutely sensational, and if the choreography wasn't memorable, I didn't particularly care. Pure bliss, and I caught the show twice more during its brief Broadway run, standing outside the cavernous Gershwin theater in the freezing cold for rush tickets in its last week. I would later have one of my Playbills autographed by Comden & Green when I saw them at Joe's Pub (another treasured memory; anyone who doubted that theater can do miracles only needed to see how the two of them shed 40 years each when they came on stage, and unfortunately, how quickly they regained them when they left.) Close second: the Irish rep revival of "Finian's Rainbow," which caused me to petition the Oxford English Dictionary to re-define the adjective form of the word "sublime"
Most magical play: a production of Shakespeare's "Cymbeline" at the Pearl Theatre in the East Village (circa 1995). Shep Sobel's minimalist vision (a trunk a la the Fantasticks, strips of cloth representing uniforms worn by different sides, and a 10-member ensemble performing full war scenes) was just magical. I saw it five or six times (plus a few half-times from the wings) when I interned there, and I have not seen Shakespeare as wonderfully done since.