• Go through immigration (TG staff will escort you from the plane through FastTrack).
• Take the underground passage B1 to Novotel Hotel (4 minutes). TG staff will walk you most of the way if you ask.
• Next morning reverse the process.

It's a breeze. I do it 3 or 4 times a month. I usually make it from the plane to the hotel room in about 20 minutes. In the morning I try to get in a quick swim and then checkout around 6:40 to catch the SGN flight.