I stayed at the Saigon Sofitel last Summer and would agree with all of the positive comments and the easy status upgrade experience.
What I was also amazed was the hotel offered a free bus shuttle into other parts of town. We used this twice thinking we would have to wait. I phoned the lounge and was told to go to the lobby - I was surprised to see the hotel Mercedes ready to take us into town. On another occasion the doorman paid a taxi for the same trip, I assume the Mercedes wasn't available.
This is the only second hotel I have stayed at where you receive champagne in the lounge.
I will stay again when I am in Saigon.