The Vietnam honeymoon tours I'd actually recommend are the ones that don't try to show you everything and instead focus on depth in one or two regions. Maybe just the north with slow days in the highlands and Hanoi, or just the south with the delta and less-trampled beaches. Vietnam couple tour package experiences that resist the urge to be comprehensive tend to feel more intimate somehow, you're not performing the honeymoon you're just living in Vietnam together for a bit.