Who the Devil Cares What a Woman Wears?

How does one make a musical around clothing? How does one make clothes the centerpiece of the show, especially when you have someone like Katherine Hepburn in the starting role? Here's a clip from the 1970 Broadway musical Coco. This video includes great costumes (some of them, I'm not sure which, are Chanel originals) and an innovative use of sets and choreography.

By the way, what a great poster.