The Cocktail Party has many different elements that make the play quite universal, without losing its unique flavor.
The reader can connect universally to the play because it features realistic characters going through realistic problems. The plot is centered on the marriage of Edward and Lavinia. The marriage of Lavinia and Edward has collapsed for reasons that we first do not quite see. Later on we realize that they both had been cheating on each other, but that none of them faced their individual problems in order to fix the situation.
The rest of the characters seem to display similar self-identity issues. This clearly brings out a collective question, as well as one of the main themes of the play: Are we supposed to stop our own life journeys just to comply with the expectations that society places upon us (such as marriage)? Or, are we exempt from fulfilling the social expectations of others in order to get to know ourselves better?
Concisely, The Cocktail Hour is a play that explores themes with which the audience can definitely connect. It does it in a comedic way which engages the audience. In all, the play does a great job at delivering its main theme, and the characters are realistic and rich in descriptors that could apply to the average audience, or reader.