If you want to meet local people, stop by a school. In Ho Chi Minh City aka Saigon, visit the American Language School, where you'll be welcomed enthusiastically and invited to go into a class and say hi. You'll feel like a rock star.
The Vietnamese love to meet new people, and teachers welcome the opportunity for their students to meet foreigners.
An excellent novel set in modern-day Vietnam is "Dragon House" by John Shors. Dragon House is the story of two Americans who travel to Vietnam to open a center to house and educate Vietnamese street children.
Former BBC reporter in Hanoi, Bill Hayton, has written a good introduction to most aspects of life in Vietnam - the economy, politics, social life etc. It's called Vietnam: rising dragon and was published in May 2010.