OP said Saigon.
Excuse me, it's Saigon I plan to go..
learn to drive moto cycle,they got a lot,buy some mini green lemons in the street,it stimulate your appetite.
@A.W Thank you so much for the advise! Probably I'll go to both Saigon and Hanoi. Now I'd better to check those websites first. :))
@Me in Beijing. Thx very much for those details, they are really useful for me.
@A.W Again, thx. I have to visit Hanoi after all you have said. By the way, Happy Thanks Giving!