That is a long long long trip by bus -- overland at least two and a half days. You'd need to go to Phnom Penh first, then Ho Chi Minh City then north to Da Nang (which is the jumping off point for Hoi An ).
Depending on how much time you have you could fly either Siem Reap to Saigon then Saigon to Da Nang, or else Siem Reap to Bangkok then Bangkok to Da Nang. Overland I'd suggest bus to PP/Saigon then take the train north to Da Nang.
thanks so much! we are now planning to fly bangkok to siem reap, siem reap to phnom penh, a few days in phnom penh, then take a boat/bus to saigon, spend a few days in saigon, then take train up to da nang and then hoi an. much more relaxed trip!
#3 caseyrebecca has been a member since 22/4/2008. Posts: 10