Seoul is a pleasant city where it is good to live. You do not feel the spirit of a capital or a huge megalopolis. People are welcoming. The culinary traditions are tasty. The temples and historical sites have their charm. The transportation is easy to use. The city is scattered, so it's not easy to visit. You have to plan to visit district by district. The Seodaemun Prison is an incredible museum. N-Seoul Tower is one of the spot to visit if you want to have a large view of the city. It's better to reach it by walk across the mountain.
Busan is totally different of Seoul. There is one feeling of holidays when you visit this city. The city is a port. The difference in temperature is felt between Seoul and Busan. The cultural village Gamcheon, in the South of the city, is to visit. It is all the more beautiful at the end of the day with the sunset. The park Hyatt Hotel in Haeundae district offers you one view of the main bridge and the opening on the sea. The bay and the bridge with the two storeys is amazing. For me, Busan is a nice place in summer time if you want to enjoy the beach and city in same time.
Daegu is a nice and quiet city. One of the main axis of this city is the pedestrian street in the district of Bongsan. You will find shopping and restaurants. If you want to have a Afternoon Tea, I advise you this place in the downtown "C'est ici"held by a lady. She makes tasty macarons with talent.