Tulum's coastal ruinsConsistently the top recommendation for visitors, and worth allowing a half day rather than squeezing it between other stops.
Local culture beyond the checklistXcaret Park and the cenotes outside the city are where Cancun feels least like a tourist itinerary and most like the actual city.
A well-known second stop: Isla MujeresRounds out a first visit nicely alongside the bigger-name sights.
Easy onward travelCancun's transport connections make it simple to extend the trip into the rest of Mexico if you have the time.