An excellent way to see the city in an evening (particularly on a cold but clear winter night) is to take the Night View Course offered by Busan City Tour. The two and a half hour long trip takes you through Gwangalli and Haeundae beaches and across the Gwangan Bridge. One downside is that the bus only makes one stop along its route, at the top of Mt. Geumnyeonsan for a photo op.
Departs from outside the Arirang Hotel directly outside Busan Station, Busan, South Korea