Seoul and Shanghai bound, late May

So I just got my tickets to Seoul and Shanghai–I’ll be in Seoul for 6 days to attend and speak at The World Editors’ Forum, and then take a trip to Shanghai, where an old friend now lives.
I need a decent hotel for Shanghai, introductions to some other folk to meet there, and suggestions on side trips, must-see places, etc.
First trip to Asia; excited about going to the world’s most wired country (think wireless broadband), and then onto a distant city I’ve heard about my entire life.