Travel Review: Vietnam, Laos, & Cambodia Tour, Ho Chi Minh City, Hoi An, Hanoi, Mekong River Delta, Royal Palace, 16-Day Trip

We would probably choose to visit Nam Cat Tein National park in a different way.  The forest was amazing (we love being in nature) and we loved our long day-hike to the lake, but there was some confusion regarding our accommodations, the requirement of a ferry to enter the park each time restricted our movement, and the planned activities inside the park did not take place as described in the itinerary. 
We would also skip the dance show and dinner in Siem Reap. Our view of the dancers was not great; many of the dancers did not seem to take their performance very seriously, and the food was one of our least tasty and interesting meals of our whole trip. 
In addition, though we enjoyed some aspects of the the cruise on Lan Ha bay (meeting other travelers, eating on the floating island, swimming in the bay) we felt it wasn't special enough, especially considering the long drive to get to the port.
We would also build in a bit more free time to explore on our own because we love spontaneous and accidental discoveries in addition to planned/toured activities.