Back to the serious, here’s some that come to mind:

42: The Jackie Robinson Story
Support Your Local Sheriff
Any of the Toy Stories
Up
Bridge of Spies
High Noon
I Love Lucy
Gentleman’s Agreement
 
Scott Walker's The Drift is operatic - and picking a record album is cheating a bit because it's already musical, even though it's not "a musical" - but it would work as a strange and avant-garde stage production.

The 1980 film of Flash Gordon as a musical with songs inspired by Queen would be awesome. It has everything - gladiatorial combat, spaceships, and whipping. Track five would be called Not the Bore Worms! and I imagine a younger Britney Spears as Princess Aura. The thought of that pleases me.
 
Valley Forge the Musical
The Alamo the Musical
Gettysburg the Musical
Uncle Tom Cabin the Musical (There use to be a thing call the Tom Show that combine Actors in Black Face, the Book and current popular songs)
The Haywood Market Massacre
The Bonus March
The Bunker the last days of Hitler
Chosin Reservoir
Tet the Musical
 
Batman v. Superman: The Musical

With audience favourites 'Martha!', 'Granny's Peach Tea', 'Is She With You?' and 'Day Versus Night'.
 
Top