I spent 2 nights in Hanoi last week. Looked for saunas and massages on the usual websites: travelgayasia and utopia-asia plus some minor ones.

Went to Polar Spa for their sauna (but their main business seems to be massage). They had over 10 massage boys in an aquarium, none of them my taste. Sauna, steam room and darkroom is small, but was well visited. Never had that much attention paid to me in a sauna, had to flee at the end (anyway there was not much area to cover and none of the customers appealed to me).

Following day met a contact from hornet for sightseeing and didn't go out at night.