Just to update my travel from Ho CHi Minh CIty to Siem Reap by 357,000 Dong bus ticket purchased from the bus company in Ho Chi Minh City.
There were other times but we pick the night bus 12:30pm to get us into Siem Reap in day light hours. Bus rep said it would take 15 hours and we will need to change bus at Phnom Penh, also we would need to wait 3 hours in the morning at the border for it to open.
at 11:45pm walked to the Bus company, went on the bus at 12:30am, not many traveller took this option about 6 in total for a full size large bus. The seats sort of recline ( so you could so of sleep, a sleeper bus would be better), the ride to the border is slow since we have plenty of time, it stopped at the border and we slept. At 07:00am the border opened, we went through along with a small group of vietnamese on their various mode of transport.
You need a photo for the Cambodian Visa at border, filled out the form and was asked and paid 22$US for the visa ( should it be 20$?).
Reboarded the same bus on Cambodian side
The bus then travelled to Phnom Penh. The bus was quite slow, but our interconnecting bus at Phnom Penh was at 12:30pm.
Arrived in Phnom Penh at 11:15am next to the tourist pier and Bus company office. Gave them my bus ticket and the Company Rep told us the bus would drop us off at thier bus station and a Tuk Tuk will take us to the market area, and was given another camobodian bus ticket.
Had lunch, then boarded the assign large bus, a little bit run down for a private company bus, the bus was full but we all had seats and the air cond worked well.
Arrived in Siem Reap 06:00pm, company bus station just east of the market area across the river. The Tuk Tuk driver was waiting for us with our names on a sign and drove us to our hotel.
So the total travel time was just under 18 hours.
Tired but uneventful trip. In hindsight if we took the bus at 06:00 am it would probable get us into Siem Reap about the same time I think as they were quoting 10-12 hour trip.