"When I'm Not Near the Girl I Love" is definitely a great pick. Christopher Fitzgerald really made that a delight in the last revival.
I agree with so many of the choices here, but one not mentioned I have to speak for is "Work the Wound" from PASSING STRANGE. Unconventional as that show is, it pretty clearly reads as a true 11 O'Clock Number for me, and a devastating one at that.
Also, I know most of these songs are solos or solo-led ensemble numbers (Anything You Can Do being a notable, and great, exception), so how would people feel if I floated "Joseph Smith American Moses" here?
Words don't deserve that kind of malarkey. They're innocent, neutral, precise, standing for this, describing that, meaning the other, so if you look after them you can build bridges across incomprehension and chaos. But when they get their corners knocked off, they're no good anymore…I don't think writers are sacred, but words are. They deserve respect. If you get the right ones in the right order, you can nudge the world a little.