In Open a New Window:  the Broadway Musical in the 1960's, Ethan Mordden surveys another decade of Broadway shows.  In the sixties, the Broadway musical got somewhat darker.  It also got much more expensive, so that a Broadway musical had to be a big hit to make money.  Among the shows of the decade were Bye Bye Birdie, How to Succeed in Business Without Really Trying, Hello, Dolly!, Mame, Funny Girl, Camelot, and Cabaret.  Lots of trivia for the Broadway musical trivia fanatic, including a lot of names that are likely to be meaningless to many readers.  Available from amazon.com.
About Broadway musicals
Other books by Ethan Mordden about the Broadway musical (available from powells.com):
Beautiful Mornin':  the Broadway Musical in the 1940's
Review
Coming Up Roses: The Broadway Musical in the 1950s
Page List johnrpierce.com
Ethan Mordden at amazon.com
In the book One More Kiss: The Broadway Musical in the 1970s, Ethan Mordden surveys another decade of the Broadway musical.  This volume may be the last in the series.  Although it is well written and demonstrates great knowledge of the subject, I found the book a little less interesting than some of the other books in the series, perhaps because I found the musicals of the 70's somewhat less interesting than those of previous decades.