Good luck to all the DO participants and I'm sure you have fun. My next trip to Korea will probably be after Chuseok in about 1,5 weeks.
The timing of the DO is kind of optimal as Seoul will be far less crowded than usual because of Chuseok and chances are sights and restaurants will still be open over the weekend. And don;t give the Grand Hyatt lobby bar a miss...
Just saw reports that 39 million Koreans are expected to travel to their honetowns and villages during Chuseok this year.