On this latest trip, driving down Highway 307 from Cancún, I see a sign for the soon-to-launch Mandarin Oriental hotel, and right after that an enormous Richard Serra–esque bronze sculpture marking the entrance to Mayakoba, a complex sporting a network of canals, a Greg Norman golf course, and a Fairmont hotel that is already open for business, with four more major properties to follow. They're triumphs in the successful campaign to brand as the Riviera Maya the zone that begins near the upper-right-hand corner of the peninsula, just below Cancún, and extends, according to the official tourist-board designation, about an hour and a half's drive south.

This notion of a Riviera is, of course—let's get this out of the way—a smart marketer's handle. Riviera lends an aura of imported chic that has nothing to do with the Yucatán's unique environment or its tough, riveting history. The idea that the region is Mayan is especially poignant, since hotel owners have tended to be foreign while many employees have journeyed here from distant, non-Mayan corners of Mexico seeking jobs. The ancient Maya may be enjoying a surprising and none-too-well-informed vogue (witness Mel Gibson's Apocalypto), but their descendants in Quintana Roo are nowhere near as prosperous as the developers whose hotels so profitably invoke them, and their culture is difficult to encounter meaningfully in a weeklong stay by the sea. Still, the name Riviera Maya has at least served to distinguish the area from nearby Cancún.

Cancún was planned—in a massive, hubristic effort by the Mexican government that started in the late 1960s—as a destination catering mostly to American visitors, with then cutting-edge notions of excitement and convenience. The project required much expansion of the beach, which, judging by Cancún's post-Wilma difficulties, appears to have left it vulnerable to the sweep of a hurricane.

By contrast, Playa del Carmen, the flagship town of the Riviera Maya, for a long time tended to grow piecemeal, by dint of individual, often European business owners. One environmentalist, originally from Mexico City, told me, "I used to party in Playa del Carmen in 1989—Fifth Avenue was a sand street of five blocks! There was only, let's say, one bar or disco at night, and everybody knew one another."

As I drive toward Playa on Highway 307, I see more signs advertising real estate than I did last year, and more shopping centers; I also know from my reading that the city has seen mushrooming neighborhoods where workers reside. Playa del Carmen is so far past the days when there was sand instead of paving that it's said to be the fastest-growing city in Latin America—a claim that's hard to believe but, if true, reflects in part the smallness from which the place has so recently sprung. Yet despite the expansion, seaside Playa has mostly hung on to its not-Cancún character, with relatively few behemoth buildings once you exit the highway, a still-strong European contingent, and a tradition of public promenading down the shop- and café-lined pedestrians-only thoroughfare of Fifth Avenue.