The long weekend of May 1 - May 5 was an absolute zoo of people. In the many years I've lived here, I guess I've just never actually stayed during a holiday haha. I took my boyfriend around to some touristy places (since he's lived here a year and never been), and it was AWFUL.
Places like Insadong and Samcheon-dong were WALL TO WALL Koreans.
I guess, normally, for long weekends I've always left the country (and when you stay for Chuseok, everybody leaves Seoul).