宿をとるべし

私もALL_NIPON_AIR_LINESさんと
同じ意見です。

大人だけなら何しようと勝手だが、
大人の都合に子どもを巻き込んで
はいけない。

出発が9時半なら宿でしょう。
深夜4時とならなら仕方ない（そもそも
そんなフライトに子どもを道連れにしてはいけない）
でしょうが。幸い市内へは近いし。

空港泊などという考えは捨てましょう。
所詮寝るだけですが。空港ホテルというものは
ありません。

First HoteかMOVENPICK HOTEL SAIGONが一番近くてまともなホテルのようです。
中心部に行っても何もできないので、できるだけ空港近くで良いでしょう。

子どもにこれを強いりますか？
The main floor for international departures (2nd floor) is closed overnight but there is a mezzanine (3th floor) open 24 hours. There is no seat to sleep on this floor except some restaurant's seats where you can sleep when the restaurant is closed during night. One little restaurant is open on this floor which is nice. Security guards stayed on the 2nd floor and they were few cleaning staff on the 3th floor.

Unlike prior reviews of the Ho Chi Minh airport, my friend and I easily found a place to crash for the night. We had 8 hours to spare before boarding a flight to Hong Kong and found a restaurant on Floor 3. The restaurant overlooked the arrival/baggage claim and had booths for patrons to dine in. A construction site sheltered our booth from the main hall and the area was dimly lit. The booths could cover our torso and thighs, however being approx 6 feet tall we implented chairs as ottomans for our longer legs. Store your luggage under the table between the two booths for safe keeping.

After reading reviews here I was expecting to be kicked out of the airport after the last flight departs at 1:30 am. Surprisingly the staff was nice and allowed us to stay. The loud vacuum cleaners and repetitive announcements were thumbs-down, but one thing good about the airport partially closed after 1:30 is that lights in some areas were turned off- which means a good night's sleep! Bathrooms are clean and have toilet paper. Benches are comfortable enough to sleep on, but I would suggest bringing your own pillow. Food in this airport is expensive- in fact there is only one eatery which bills in US dollars. Make sure you have your dinner beforehand!