Pleasant border town in the Mekong delta, to observe life on and along the river
The first Vietnamese town of any significance, when coming down the Mekong River from Cambodia, is Chau Doc. Dusty, bit of a border town atmosphere, but pleasant enough for an overnight stop. Many of the hotels are on the waterfront, and a couple of hours on the terrace provides entertainment from river life as is passes by: fishermen in canoes, small-scale ferry operators, and larger wooden barges mostly transporting rice husk.
A trip on the many canals allows visiting many other attractions: fish farms, villages, floating markets, or just passing through the many waterways in and around town, past corrugated iron houses on stilts.