Seoul and Busan recommendations

Watch both series of "The Good Detective" on Netflix then just look for recognisable places in Busan. That would be one of my dream holidays. Or just look for zombies/mystical incarnations.
Seoul has bars everywhere, big drinking culture in Korea. Lots of people speak English too, many cool little bars with live music or special decor. Foreigners used to head to Itaewon, close to the US army base, for a night out, its been a while since I was there though, so a quick search online will help.
Food is magic, the mixed rice, 비빔밥, street food, e.g. spicy rice cakes 떡볶이, the famous different bbq meats, pork 삼겹살, or beef 불고기。 Its a lot of fun is Seoul, great to walk around, the palace in the middle of the city, and the uncovered stream running off that main area, great places to wander.
It's that long since I've been to Seoul or Busan that I can't really be very helpful. Both really interesting cities, Seoul being a mega city with absolutely all sorts going on and one of those more rare places these days where you really feel like you're in a very different type of place/culture. Out of Busan we went touring some really interesting Buddhist sites.
Some interesting food to be had as well. 🐕
I use to travel into Busan to get to Geoje Island. Korea is a brilliant country with brilliant people. My experience is they love a drink and hot spicy food.

The shipyard I worked in was massive and a great experience. Thousands of people and loads of ships being built.