Recently while planning my trip to Cambodia, Laos and Vietnam, I did a little research: I am not sure about direct buses from Siem Reap. However, Stueng Traeng is about 5 hours. From there, you can get a mini bus connection to Pakse. This takes about another 5 hours. From Pakse it is an overnight sleeper to Vientiane. If you have time, it is advisable to stop over either at ST or take a slight detour to Kratie. Stay overnight here, and then get a bus to Pakse (an extra 2 hours).
I also stumbled upon this website: http://www.ppsoryatransport.com/index.php?page=service, could be useful you, though the buses seem to start from Phnom Penh. You might be able to get more information from them.
Another post I saw was about this couple who did a trip to Vientiane from Siem Reap via Thailand: http://www.travelfish.org/board/post/visabordercrossings/8753_trip-report–siem-reap-to-vientiane.
I finally dropped Laos from my itinerary, so cannot advice you from personal experience though.
Credit:stackoverflow.com‘
5 Mar, 2024
5 Mar, 2024