The role of Lila, washed-up showgirl of the title, was originally intended for Marilyn Monroe, who was replaced by Joanne Woodward upon Marilyn's death. The ironic opening sequence (undoubtedly rewritten after Miss Monroe's death) has the bleached blonde title character, upon her arrival in Hollywood, being mistaken for Jayne Mansfield by a tourist.
The original New York production under a different title was "A Loss of Roses" by William Inge which opened at the Eugene O'Neill Theater in New York on November 28, 1959 and ran for 25 performances. It starred Betty Field, Carol Haney, and Warren Beatty.
In 1961, Eleanor Parker was announced for the role that presumably went to Claire Trevor.
Warren Beatty was nominated for the 1960 Tony Award (New York City) for Supporting or Features Actor in a Drama for "A Loss of Roses" (Original title of play) as Kenny.
In 1961, Natalie Wood was announced for this film (then called Celebration), as a re-teaming with her West Side Story co-star Richard Beymer. Presumably, she would played a beefed up version of supporting role that eventually went to Carol Lynley.