I am just back from a trip to Bangkok and Hanoi and have visited both cities regularly for the last 5 years. Although i always enjoy a few days at babylon, the odd massage and visit to a boy bar in BKK, i really prefer Hanoi and i get a lot more sex there.
Although it has no gay scene beyond one very respectable bar, grindr is full of cute boys into older white guys (i am early 60's)and most are not money boys. Those that are ,tend to be upfront about it, which is not always the case in Bkk.
In Hanoi i always stay in a cheap self contained airbnb so there is no issue about guys coming round at all hours of the day and night and i usually end up hosting several group sessions, a few threeseomes as well as as much one to one as i can handle.
There are several small but busy saunas, this last trip i had several enjoyable afternoons and evening at spa Adam, which costs only 60,000 dong, not much more than 2 quid.