My Favorites

Beaches:
$: Tulum Beach - free of charge
$$: Xcacel Beach - 10 pesos per person, to help the Turtle Sancuary
$$$: Chemuyil Beach - private property, you have to pay to get access, usually 50 pesos/person

Cenotes:
$: Xu Naan Ha - 50 pesos, just follow the dirt-road to the west, instead of walking to Chemuyil Pueblo
$$: Cenote Cristalino - 80 pesos, about 15 km north of Chan Chemuyil, 5 km south of Puero Aventuras
$$$: Dos Ojos - 200 pesos, 5 km north of Chan Chemuyil
Just to cool down swim for free in the small cenote in Chan Chemuyil

Restaurants:
$: Leo´s Pizzaria in Chemuyil Pueblo: try the Fajitas de Camarones/Res
$$: El Camello, at the south end of Tulum on the right hand side! Seafood only!
$$: Turtle Bay Café in Akumal: try the flatbread after 2 pm!
$$$: La Buena Vida in Akumal, Half Moon Bay!
Best (Italian)Pizza in the area: La Nave in Tulum

Ruins:
$: Tulum: the only Mayan ruins on the sea
$$: Coba: in the middle of the Jungle! Do not miss to climb the pyramide!
$$: Uxmal: a perfect 2 or 3 day trip: spend the night in Izamal and head for ruins the next morning!
$$$: Chitzen Itza: arrive early before all the busses from Cancun and Playa del Carmen, bring hundreds of tourists

Golf Courses:
$: Puerto Aventuras
$$: Riviera Maya at Bahia Principe, just 3 km north of Chan Chemuyil
$$$: Maya Coba