Think you should count on a stopover in Stung Treng , the last town before the border which has several guesthouses. See the transport link here: http://www.canbypublications.com/cambodia/buses.htm#PP-STR.
And see map here: http://www.canbypublications.com/maps/camroad.htm
From Siem Reap your bus goes down route 6 then probably have to change buses at the crossroads with route 7 (bus going north from Phnom Penh). So it's a farther road trip than many people initially guess. I did in reverse a few years ago and even Kratie to Siem Reap was a full travel day.
Not really a good idea to do the border at the very end of the day anyway. Hit it from Stung Treng fresh the next morning and you should be on Don Khong in time for brunch.
From Siem Reap go to T'bang Menchey and from there straight to Stung Treng, brand new road, no need to go south at all and should easy be able to reach Si Pan don in Laos in one day. I did Banlung Siem Reap in 7 hrs with my own car, which is longer distance than SR to Laos border.
Dunno about public transport
stop over in kratie or stung treng. even with the new road, public transport are not that fast and remember - border post closes 6 p.m. sharp! after that it gets dark quickly and therefore - don khong is almost impossible.
ferry port is ban nakasang - this is 1 hour away from the border!
#4 chaos23 has been a member since 4/9/2008. Posts: 17
Back in February I did a similar trip... Siem Reap to Don Det..left Siem Reap at 5am, mini bus to somewhere, transfer to bus which took us through the border (arrived around 5:30pm) then transfered to another mini bus which took us to the port where we got a boat to Don Det but there were others in our group that went to Don Khong...just a warning- it was dark when we arrived at the port so they had to convince the guys to take them over in the dark and pay extra...otherwise, it's a long day but it's possible.
But maybe this new road from post #3 will speed things up. We just asked at our guesthouse and booked through them. Everything was arranged for us and included in the price.
#6 dano_b has been a member since 20/12/2009. Posts: 24
Thank a lot everyone!
#7 smach has been a member since 10/9/2010. Posts: 2