In Hanoi go to see Ho Chi Minhs home and tomb. Also make sure you visit the park in the center of the city, there's a lovely little spot on it where you can sit and have real hot chocolate and to die for Vietnamese coffee. If you get a chance get up to Ha Loong Bay, it's one of the wonders of the natural world and gives you a great opportunity to see some beautiful Vietnamese countryside.

There's also one of the oldest universities in the world in Hanoi, so that's a must see too.

And don't forget to eat pho from a street vendor. :)