You’ll probably want to pick a home base (or two) for your time om the Riviera Maya , and make day trips from there. Playa del Carmen  is the area’s only real city, with all the expected urban amenities, including nightlife. (It’s also the gateway to Isla Cozumel .)
Puerto Morelos  and Akumal  are smaller but still have a decent selection of hotels and restaurants. (In fact, if you’re a foodie, Puerto Morelos has a surprising number of first-rate restaurants.) If isolation is more important than convenience, the Riviera Maya has some secret getaways, like Xpu-Há  and Tankah Tres .
If you’ve got a week or more, consider spending half your time in the northern section—around Playa del Carmen, for example—and then move farther south, to enjoy Akumal, Tankah Tres, and even Tulum .
A rental car isn’t absolutely necessary but will certainly make exploring the Riviera Maya a lot easier. Cheap public shuttles zip up and down the coast, but they only stop along the highway, which in most places is about a kilometer (0.6 mile) from the ocean. That leaves you to make the hot dusty walk up and down the access roads, especially in more rural areas where taxis are uncommon.