I have. had four trips to Vietnam in total.
The first one was interesting at times, the second was really interesting and resulted in a dose of Lead Poisoning, the third was very pleasant, and the fourth was just amazing.
On the fourth we visited the very Northern part of the country including Dien Bien Phu and worked our way south to Saigon by means of Bus, Van, Car, Sleeper train, and airline flights....with a stop in Hanoi where we took in the sights that included the Hoa Lo Prison (aka Hanoi Hilton), the site of John McCains capture, Ho's Tomb where he is preserved an on display.
In Saigon we took in the museums, old Presidential Palace, and the old Rex Hotel....and some really nice restaurants and bars.
I stongly encourage Vietnam War Veterans to go on a two or three week hour tour of the country and get a set of memories they will know as Vietnam Redux.
My notion is the human mind draws from recent and/or pleasant memories before it brings up old and/or unpleasant memories.
It works that way for me.