Jerome Robbins had final say over the casting and--genius though he was--some of his ideas were peculiar, to say the least.
He wanted to the Jets to be "all-American," which ended up making them look like a midwestern Boy Scout troupe. (A gay midwestern boy scout troupe.) One of the Jets, the very clever Brian Kaman who played Baby John, made up a parody lyric that went "When you're a Jet, / You're a Jet all the way, / From your first pirouette / To your last grand jete."
Robbins and Bernstein fought over the casting. Laurents and Robbins fought over the acting. Sondheim paced. Peter Gennaro, Gerald Freedman, Lee Theodore and Tommy Abbott carried out Jerome Robbins's directions. Ruth Mitchell carried her stage manager's book from the 1957 production and would say to Debbie, Josie and Ken: "Chita, you move stage left. Carol, stage right. Larry, stay where you are."
One day Peter Gennaro actually brought Chita in to show Debbie how to do some of the flourishes he had forgotten. Chita remembered them ALL. By the end of the day, Chita and Debbie were dancing "America" together.
Me? I was someone in a tree. I saw EVERYTHING.