For me, it would be "Side By Side By Side" from the 1970s staple, Company. A second act opener that redefines the love between Bobby, the prototypical swinger, and the five married couples that make up his social orbit, it starts out as a slow ballad, moves through a series of alternating fast and slow sections, and ends up with a rousing tap dance number that leaves Bobby (literally) hanging in the wind.
Music wise, my part (clarinet/bass clarinet/baritone) started out with a bouncing accompaniment to the muted trombone solo line under the opening vocal. Then, it's a series of horn swaps through the sections dealing with Bobby's problems, ending up in the big tap dance finale.
One of the clarinet sections was a lead part over the rest of the woodwinds on saxes, so I subbed in a soprano sax on that section with considerable effect.
All in all, the song had everything - Sondheim lyrics, classic American musical style, a great deal of humor (ending with the spectacle of Bobby's turn in the tap dancing spotlight, when it is suddenly realized by the entire audience that he, alone among the eleven principal cast members, has no partner to finish up the end of his sequence), and a nice bass clarinet line.
