Loved HaNoi - disliked HCM, although my son loves it. He was there last month, and went to a cafe where the owner was an agent for the North Vietnamese, but the main patrons were GI's on leave. While they were downstairs eating, the NV were upstairs plotting the TET offensive! The cafe is now owned by the son! Of course, they are heroes in Vietnam. And on the walls are all the original photos etc. Amazing.
HaNoi is like going back to the past. Everyday their speaker system throughout the city blasts off with communist propaganda. Do the walking tour through all the original city streets. Hanoi has the best French/Vietnamese restaurants. Do a 1 day Junk tour on Halong Bay. Vietnamese Airlines are WAY better than our airlines here. Planes are new, with lots of room. You tend to catch a plane to visit all the tourist areas. Visit HoiAn for a lovely beach DaNang). Skip NhaTrang - dirty and sleazy.
Having grown up with a teenage brother at the time of the Vietnam War and conscription, going to Vietnam was an amazing experience.