Because the layout of downtown Playa is a rectangular grid, getting around is very easy.
The main east-west street, Avenida Juárez, connects Highway 307 with the town square, El Zócalo, near the beach. As it does so, it crosses several numbered north-south avenues that run parallel to the beach, all of which, interestingly enough, are multiples of five. Quinta Avenida Fifth Avenue, the closest to the beach, is closed to traffic from the Zócalo to Calle 6 and some blocks beyond, in the evening.
Almost the entire town is north and west of the town square, El Zócalo. The east-west streets parallel to Avenida Juárez are numbered Calle, with even numbers to the north of Juárez and odd numbers to the south. The other main east-west street Avenida Constituyentes is located where you would expect to find Calle 18.
To the south of the downtown is "Playacar" a golf-course development of private residences and a dozen resort hotels.
On foot
Playa is pedestrian friendly town and you can basically walk to everything. The main north-south pedestrianized street, 5th Ave, does not allow cars except in the early morning hours for deliveries. On 5th Avenue are many hotels, restaurants, and small shops. The north-south thoroughfare Avenida 30, five blocks west of 5th Ave, is where the large stores are located. To walk from the town square, El Zócalo, and Avenida Juarez to Avenida Constituyentes takes only about 10 minutes.
A bike is a fun alternative to walking; there are a number of bike rental shops at the north end of 5th Ave.
By taxi
5th Ave. 'Quinta Avenida' or '5ta Av.' is a pedestrianized street and taxis are available at various intersections along its length. A taxi taken from a 'sitio' place where taxis park will cost a few dollars more than a taxi hailed on the street. It costs US$5 to get to Playacar, and about US$1.50 to get around the rest of Playa.
By car
Car rentals are readily available at a number of locations at the north end of 5th Ave. Large companies, National, Hertz, etc. are convenient, as well as local agencies, which are generally less expensive.
By bus
Scheduled bus service to destinations in the region e.g. Xcaret, Xel-ha, Tulum, Cancun airport, Cancun, etc. and beyond depart from Playa bus station at southern end of 5ta Avenida and Avenida Juárez, which is near the Ferry terminal to Cozumel.
First class ADO bus departs hourly or so for tourist destination of Xcaret, Xel-ha and Tulum - fares are in US$4 range. The ADO Bus goes directly to the entrances of Xcaret and Xel-ha. ADO also runs direct service to Cancun airport from Playa Del Carmen for approximately $116.
Second class local Mayab buses also leave from Fifth Avenue station. Mayab buses stop more frequently enroute and drop off alongside the highway to Tulum, requiring walking from the highway to the entrances of Xcaret or Xel-ha.
An alternative to the buses is to catch a "colectivo" van. These leave/return at Playa from a location on Calle 2 between Av 10 and Av 15. Colectivos are cheap government regulated air-conditioned vans which transport people on Hwy. 307, which runs north/south along the coast between Tulum and Cancun. Pick-up times for these collectivos vary, roughly every 10 minutes, and pick-up/drop-off is simply along the freeway; but one can get you a ride near to any destination between Tulum and Cancun for as little as US$3. There are also vans either ran by individuals or tour vans returning empty from a drop off that will pick you up along side Hwy 307. The easiest way to catch one is to wait at a bus stop and extend your hand out like a handshake. Sometimes a van will flash their lights which is asking if you want them to stop. Prices vary, but can be as cheap as $3. They pickup up and down the entire length of the highway. Most all speak English. They drop you off ONLY along the highway at your choice. No door to door service.
Organized bus tours are also available from a variety of companies that cross the Riviera Maya & Yucatan Tulum, Cancun, Isla Mujeres, Mahahual, Ek Balam, Celestun, Rio Lagartos, Merida, Chichen Itza, Uxmal, Coba, Sian Ka'an, Xcaret, Xelha, etc..