I will be arriving at around 11:45 PM at Incheon and will need to get to Hongdae afterwards. I looked it up and AREX closes at 10:45 PM but there would be buses that are available at around 12-1:20 AM to Seoul Station. Would there be local buses around this time or will I just have to resort to hailing a cab?
Depending on what time you get to Seoul station, you can:
- Catch the metro from Seoul Station > City Hall station > Hongik University station. I believe the last subway is at 12:45am-ish. You can download the Kakao Metro app to have a look and double check.
- Stay at a jimjilbang (Korean spa house) around Seoul Station for the night and then move to Hongdae in the morning. There's a jimjilbang called Siloam Sauna (http://english.visitkorea.or.kr/enu/ATR/SI_EN_3_1_1_1.jsp?cid=610005) which is within walking distance
- Catch a cab like you've stated.
I personally think it's okay to catch a cab. I haven't had any problems catching a cab at that time of night when I was in Seoul.