The culture is very homophobic because they do not want their own kids to be gay and families with gay kids are looked down upon by the entire community. But this is the case with many Asian cultures. The government also cracks down on places where gays may meet but they also crack down on homeless beggars and street prostitutes routinely sending them to "re-education" camps. If you are a caucasion you have immunity from most of the expectations of Vietnamese and expats except for serious things like drugs, etc. If you are Asian make sure the passport control people are aware you are not a Vietnamese expat or they will shake you down for bribes in order to leave the country (this should only happen to Vietnamese expats). My Vietnamese partner gets shaked down for bribes even at late as November 2007. As a caucasion in the several visits to Vietnam (1999-2007) I have NEVER even had a look from the policemen HOWEVER while in Japan I have been stopped twice and had my passport checked while just walking down the street.
What is nice about Vietnam it still has a good exchange rate pegged at 16,000 dong to one USD but prices are higher everytime I go back thanks to European (and now Canadian) tourists but I think it is one of the better values still remaining in the world for American travelers.
We always travel as a couple but typically are given two beds in the very small places we stay in but even that can be nice when it is so hot all year round. You should not have any issues since you are not held to the same standards as the Vietnamese place on each other since they are very concerned about their "face" in the community.