Final answer:
The important Big Five traits for someone who enjoys hosting impromptu parties are Openness and Extraversion, which involve creativity and a sociable nature.
Step-by-step explanation:
The Big Five traits that would be important for someone who often entertains others with impromptu parties are Openness and Extraversion. Openness involves creativity and curiosity, traits that are beneficial for coming up with spontaneous party ideas and enjoying diverse social interactions. Extraversion is characterized by being socially energetic, which is crucial for hosting and enjoying the company of guests at a party.