You can get a sleeper bus from Vientiane to Pakse for 170000 kip. It's reasonably comfortable and there is a toilet on the bus. The buses depart the Southern Bus Station at around 8:30 p.m. and arrives in Pakse around 7:00-7:30 a.m. If you don't buy the ticket before hand then you need to arrive early to buy it-they generally sell out. When we have booked tickets over the phone and turned up to pay before departure they have told us to come by 7:00 p.m.
Some of the buses are nicer than others. If you are over 1.75 metres tall then your feet and head will touch the end walls (padded) and it might be uncomfortable. You have to share a bed (same sex sharing) but you could buy two tickets and get the bed to yourself..big it ain't.
They'll give you a bottle of drinking water and a cake for the journey. Lights out soon after departure. When it's good, you fall asleep about 9 or so and wake up refreshed in Pakse the next morning...when it's not you don't...Staff can't speak English (on the bus or at the ticketing office).
