I flew to from Hanoi to Hue, and got a driver to take me from Hue, through Danang, to Hoi An. Then got a driver from Hoi An to Danang airport, to SGN.
The drivers and hotels in Hue and Hoi An were booked through
www.buffalotours.com Hotels in Saigon and Hanoi were booked through my SPG account.