I hate musicals too. Walked out of more than my share -- just unable to take it. "Cats" made me want to kill myself so I wouldn't have to be conscious while walking out.
That being said...I saw Man of La Mancha with the original dude playing Don Quixote -- My mom took me when I was 14. Basically, he's an old man going senile who thinks he's a knight, fighting bad guys, etc.. And the story is mostly other people laughing at him. But damn, it was awesome. And the lyrics to "The Impossible Dream" are freaking fantastic:
View: https://www.youtube.com/watch?v=OHVGOp5Usv4
A movie that technically counts as a musical is "Once" -- it's set in Ireland and follows this Irish busker who meets this girl. But the music is organic to the story so you don't get the "people walking along and then start singing out of nowhere" bullshit. Small-scale independent film that my wife got it because she liked the cover, and it was fantastic.
But every other musical ever created seriously