Three largest international airports in Vietnam are: Noi Bai Airport, Da Nang Airport and Tan Son Nhat Airport.
All operate with rather high records of courtesy and efficiency. They provide basic, pleasant-to-use facilities/ services including business lounge, Internet area, exchange bureau, ATMs, Tourism information help desk, etc.
ADDRESSING THE TAXI RIP- OFF AT AIRPORTS
1. Make sure you get a metered taxi.
2. If your destination is somewhere other than the airport or a major hotel, it might help to write the name and/or address on paper beforehand.
3. Carry small change and bills for paying fares, since drivers often pretend to be short of change.
4. If you get stung by a dodgy taxi driver, meter or not, you can refuse to pay. This might lead to a heated situation, but eventually he has to take what you offer.
5. Make sure you get the taxi number and report it to its operator or the police if you think you have been fleeced.
6. Ask hotels for recommendation of creditable taxis.
7. Hotels also provide city maps with the names of company taxis on the back. They are distinguishable from private taxis by the phone number on the side which is much longer. (from TripAdvisor)