Le' Miserables' by Victor Hugo has always been a literature-play classic. However, for me, the musical-play that surpasses the timeliness of Le' Miserables' is Cats.
Cats has been one of the most successful plays which was able to beautifully merge music, acting, and acrobatics in one. I remember my Grade 6 days wherein we presented Cats back in our school. It was a lot of fun projecting like stupid cats (I'm not good in acting so why did they have to choose me?)
The best songs in Cats are the opening song Jellicle Cats and the Mr. Mephistopheles' character song. Of course, the song Memory (Grizelda's character song) brings out the tear in anyone who will listen.