To ask if Maya ruins is worth a visit is like asking is the Great Wall or Forbidden City worth a visit. There are Maya ruins all over Mexico and there is even a small one in the Cancun hotel zone. Definitely go to Chetchnitza (by the way it's a World Heritage site). You can sign up for Chetchnitza tour in the hotel zone.
As for the 2nd question, how many days are enough for Cancun? It's really a personal preference (the same for any place, in my opinion). Everyone has different things they like and different things they want to see. I spent 6 days in the Cancun area, alternating between day trips to islands/Chetchnitza and relaxing days on the beach without doing much. I did not plan to do all the activities and see everything Cancun has to offer.
As for the 2nd question, how many days are enough for Cancun? It's really a personal preference (the same for any place, in my opinion). Everyone has different things they like and different things they want to see. I spent 6 days in the Cancun area, alternating between day trips to islands/Chetchnitza and relaxing days on the beach without doing much. I did not plan to do all the activities and see everything Cancun has to offer.
