Songs I have heard pretty much constantly in Vietnam:

1. Hotel California. Mostly the (seemingly extended) live version. It just goes on and on and on.

2. Dancing Queen by Abba. It always seemed so incongruous, no matter where it was being played.

3. The theme to the Godfather. 

3. Muzak versions of the above and more. I remember receiving one of
the best massages in the Blind Association School in Nah Trang, and
during this almost spirital experience having Muzak version of Abba
songs being piped through the soundsystem. Very relaxing.