Skip the palace day
You already did the palace. Do not schedule Gyeongbokgung and Bukchon again. Pick one alley, and only one: Dosan and Cheongdam, the Seongsu back streets, or Gwangjang at night. Do not open Garosu-gil, Seongsu and Jamsil the same day. If you pick Gwangjang, that is the centre night. Do not transfer to Hongdae or Dongdaemun for a second one. If you pick Seongsu, one coffee, then Seoul Forest, and no tower. If you pick Dosan, the avenue ends there. A return visit is worth skipping a palace, not finishing the three south lines you missed last time. Once the alley is chosen, the others wait for another trip.
One river evening
After the alley, one river evening: Yeouido, Banpo or Ttukseom. If you want the tethered balloon, add it only at Yeouido. It is not a second tower. Do not put N Seoul Tower and Lotte World Tower on the same dusk. If this return visit is skipping towers, do not climb one just to fill the view. Magok is not on this map. It is another day, not the Yeouido evening. Check the Hangang bus the same day. No fare is printed here. Sit by the river until the wind comes up, then go back to the district where you sleep. Do not write Magok, the end of the Hangang bus, into tonight. It is not a place on this map.