I've stayed at the Hanoi Hilton several times, and have gotten a rate of USD75. Contact the hotel directly and negotiate. When we were arranging the first visit, they offered us $85, but Metropole gave us a quote of $80, so we bargained it down since Metropole is a better rated hotel than the Hilton Hanoi.
A good hotel, but I really didn't like the green colour scheme! On a couple of occasions I've gotten rooms with a mini-balcony.
Am not very impressed by their in-house dining, there are too many great restaurants in Hanoi. But I do adore their lotus shoot salad (ngo sen thom thit) on the room service menu! I don't always have the chance to dine at a Vietnamese restaurant that serves lotus shoot salad so it's nice to be able to have it at the hotel. Oh - and the plate of welcome chocolates is always a nice treat!