If you don't want to see these countries on a big bus tour, I recommend working with AOJ on a custom trip. Our group of 6 worked with Vinh to set up a wonderful journey throughout Vietnam with additional stops in Siem Reap and Luang Prabang. Vinh was very easy to work with and together we planned our trip via email. He had great suggestions and was flexible to accommodate our wishes. Hotel selections were outstanding, and our guides/drivers in each place were very knowledgeable, helpful, and flexible. Our two week trip went very smoothly. The one little problem was immediately resolved. (Allow 3 nights/days in Siem Reap!!)