Tell Me Where to Go in Seoul and Tokyo

On the 13th, I'm flying to Seoul for a Samsung press junket. From there, on the 19th, I'm going to Tokyo until the 27th to see what kind of fun stuff I can find. Having never been to either Korea or Japan, I need some help from you nice folks: what stuff should I absolutely not miss? I'm bringing a video camera as well as a still camera and plan on doing a number of reports from the field. What do you want me to go check out and report on? What are you curious about? What things do I just need to see? Help me help you, friends. Tell me what you're interested in and give me tips, and I will dutifully follow up for you. ^_^ keke!