A Weekend in the Country from A Little Night Music... There's this wonderful "SYKE!" moment where Desiree and her daughter are discussing their weekend get together at their home, and they discuss whether or not one of Desiree's jealous suitors will "come galloping up on a black stallion brandishing a sword?" "No, it''s his wife's birthday this weekend. Sacred to domesticity. At least we're safe from him." And then I imagine Steve's face popping up saying "SYKE!" (because of what happens next)
It doesn't make me cry like Children and Art does, but Franklin Shepard, Inc is such a theatrical rush of emotion and fury that I find myself returning to it over and over. It's glorious, this eloquent outpouring of sarcastic rage, it's totally electrifying. Especially in the original performance by Lonny Price, who's like a live wire.
"Now You Know" - it's not (in my opinion) his greatest musically or lyrically, but it's the one that means the most to me. In fact, I love pretty much everything about the OBC of Merrily (though I have no reason to doubt that the production itself was a complete disaster.) That recording - with all its energy and effervescence - helped me get through a rather terrible time in my life.
Really hard to choose between about two dozen absolute favorites but I'd have to go with the song that has made me cry (in both acts) all three times I've seen the show live. That'd be "Sunday."