Butterflies away MASH. The POW-MIA flag thing would probably never happen. No Rambo (or Chuck Norris analogue) movies. The US remembers Vietnam much like Korea. The US would see its role in propping up pro-western governments as justified. The US might be much more aggressive in Latin America and against Iran. The Iran hostage situation would never happen, or if it does it means war and the US can easily take out a nascent Ayatollah.
Ironically, this may butterfly away the 80s military buildup as some postulated, so the US will not necessarily be in more debt, but the US will have more hubris. It becomes hard to postulate what the next war would be. If Iran is knocked out early, then Iraq is never propped up. This means no middle eastern adventures, and this butterflies away 911. The US would probably still support bin Laden against the Soviets, but the impetus for him to attack the US in this situation is much less and may never occur.
However, how does the US respond to embassy bombings and such? I cannot help but think that occupations may begin. If this occurs, then the US is on the road to OTL fighting wars all over the world it cannot win. Without a bunch of Vietnamese and Khmer refugees in the 70s, the current refugee "crisis" may be responded to with even less enthusiasm--if it even occurs, as the US might not see the need to take out Qaddafi and Syria.