We are going to Vietnam and Cambodia for two weeks. Most of the itinerary is set in stone, but we have three days to use that we can't decide on. We would either go to Ho Chi Minh for that time which would include a day trip to see a floating market in the delta OR we would spend the time seeing the UNESCO sites in Hoi An, Hue, etc and maybe stay in China Beach somewhere for some time with the sand. Pros? Cons? Anything helps!
To get a sense for what we are already planning, we are going to Hanoi, Halong Bay, Phu Quoc, and of course, Siem Reap for the Angkor complex.