Certainly casting is paramount in the production of a movie. For, there have been movies that were good, but made memorable by the stellar performance of an actor/the actors. In the 1968 film "Romeo and Juliet," directed by Franco Zefferilli, the unknown actress who played Juliet stunned the world as she seemed to embody the innocence and beauty of Shakespeare's fair maiden. The modern interpretation given to this film by Zefferilli is also part of the great appeal of this film. And, this is true of the appeal of "West Side Story," as well. Placing the play into the musical genre with gangs as the feuding families was certainly successfully creative. So, in this case, script is a salient element.