What kind of cocktail party? Who is throwing the cocktail party? Who is attending the cocktail party? Where is the cocktail party being held? What is the occasion for the cocktail party? What kinds of drinks will be served at the cocktail party?
I'd say throw one yourself or find out if your friends know of any cocktail parties and attend. When it's a relatively easy-to-have experience like a cocktail party, it's probably better to create an original scene from something real that you can experience firsthand rather than recreate a scene from something already published. Don't be afraid to invent.