A trip to the Great Wall is definitely worth it. Not too far out of Beijing. Your hotel should be able to arrange it.
On jade, the Asians consider the light, translucent jade to be the best, not the dark, opaque green jade you often see. I don't know much about jade but I lived in Asia for a while and that's what I was told.
I was in Beijing maybe 7 years ago and it was a booming place. With the Olympics coming, I'm sure it's booming even more. It's an interesting place - I hope you enjoy it.
Go into the world and do well. But more importantly, go into the world and do good.