Last night in Seoul, flight departing Incheon at 8 PM... What should I do?

I will be spending the weekend in Seoul and need to catch an 8 PM flight at Incheon Airport on the last day. However, I want to enjoy the last night, so I'm considering how to make the most efficient use of my time. The options I'm currently considering are partying all night and heading straight to the airport, staying at a hotel near the airport, or departing from Seoul in the early morning. I would also like to know which areas are convenient for traveling to Incheon Airport while enjoying the nightlife. Which is better among Gangnam, Hongdae, and Itaewon? I would appreciate advice from those who have experience with this. Additionally, if you could recommend any bars or clubs, that would be great.