The South of Laos
But for what I have seen from the bus, the charm of the place was well hidden... And for most people, this place will be remembered as a trap where most very basic accomodation without shower cost around K50000 ( even so there is apparently a cheaper one at K10000 in the bus station to Vientiane...)
Also, to get a seat on the next day bus may be problematic. Most likely you will get a plastic chair in the alley...
It is however possible to cross the Mekong to Nakhon Phanom in Thailand. But this place isn't too exciting either...