Rundown will have to do since I can't find it in my local library
Please and thank you
Okay.
Unfortunately, there is no good POD placed into "Suppose They Gave a Peace" that realistically would have given McGovern a chance to win; the election seems to occur much as it did in OTL, with Eagleton among other things. However, Nixon apparently kept a significant number of troops in South Vietnam rather than withdrawing them all over a period of time (I imagine maybe ~200,000) and having them deployed into active combat positions.
Growing Casualties in Vietnam is also combined with a growing reluctance in Hanoi to go forward with the Paris Peace Accords as McGovern edges closer and closer to Nixon in the polls, despite Kissinger saying that "Peace is at Hand". Eventually it comes down to a squeaker and an extended recount that Nixon narrowly loses to McGovern.
With McGovern now being confirmed as the next President of the United States, the North Vietnamese begin to view the United States as a "Paper Tiger"; basically, since the United States is withdrawing from Vietnam no matter what they do, they have no reason to hold back any longer. While the United States is withdrawing from the country, the North Vietnamese begin an invasion over the DMZ and take control of much of the countryside. Efforts to contain them are made even more difficult when McGovern basically forbids the military from using Napalm or DDT. South Vietnam as a nation disintegrates while refugees try their best to follow the Americans out of the country, jumping onto the backs of cargo planes, wading out into the oceans to meet waiting offshore vessels, complete and total chaos.
The "Withdrawal with Honor" fails miserably as it was initially envisaged, being called the "Long Retreat".
The story itself takes place in Ohio among a politically splintered family. The father is a Nixon men who is a Korean War Vet, deeming the Vietnam War a necessary conflict. His daughter meanwhile is the opposite, a well-mannered (no drugs) Hippie, who supports McGovern and is against the War. His son meanwhile is a Marine who has been deployed to Saigon as a member of the Embassy Guard. As the story develops, we see the effects of the war and the toll they take on the psyche of the family, especially when the son placed his 'secret' Vietnamese wife on the last helicopter out of the embassy during the 'Liberation' of Saigon.
Again, I can't really do it justice.