Singin' in the Rain, the Wizard of Oz, West Side Story, Grease, The Music Man, the Producers. The Rocky Horror Picture Show...if you're into American History 1776 and Hamilton are both good options. I've only heard the Original Broadway Cast Recording for Hamilton, though. Haven't tracked down any recordings of the production itself because Iris would be upset with me if I found a way to watch it without her.

Haven't had a chance to see any 31st century musicals, unfortunately. Been a little busy, and nobody's suggested any to me.