Just a few more...they're not all rare, and they weren't all flops, but they're not musicals the average non-musical fan would know (As in, they're not Oklahoma, Les Mis, Phantom, or Wicked)
The Goodbye Girl
I'm Getting my act together and taking it on the road
The Life
Marie Christine
A New Brain
Randy Newman's Faust (concept cast)
Starmites (I bet you'd really enjoy this one, if you don't have it already!)
There's always room for pathos - and jazz hands.