The drive south from Bangkok to the seaside town of Huahin took more than a couple of hours, and Phetchaburi, a small city that has established itself as a destination for traditional Thai sweets and snacks, lay at the perfect distance at which a car-bound family needed to find a clean enough bathroom. You could stop at any of the roadside stands or storefronts to stretch, replenish, and look over table after table of pineapple-filled cookies and pandan-scented rice cakes. City people filled their arms with tall stacks of kanom mor kaeng, a coconut-and-palm-sugar custard steamed in metal trays that is the pride of the region.