We didn't do the ATV but did visit a cenote as part of our tour of Chichen Itza. It was beautiful and very refreshing after a day in the sun. We booked it at the resort.
This was the link that I posted yesterday to the company that has lots of the more extreme tours. I haven't done the ATV one personally, but everything else I have done through them has been well put together and worth the money. https://www.cancuncare.com/tours/xplor-cancun/ The one other thing that I did mention yesterday, is that if you are only at the resort for like 6 nights, and you're planning on the Boobs Cruise, it's probably unlikely that you are going to want to leave for another full day excursion. (Just some food for thought based on personal experience. I normally reserve most of our excursions for when we are down for family vacations.)
I did the ATV cenote trip on a recent family trip. It was a lot of fun but like Steve said it eats up a whole day and you are tired when you get back.
We cast another vote for sticking to the resort if you're staying less than a week, especially if your flight times eat into the first/last day much. That said, if you do venture off for a day trip it can be an eye-opener to return late afternoon, as we did for a scuba diving excursion during our 2nd trip. With diving you're not supposed to consume alcohol prior to the dive, and obviously not during. We returned to the resort around 4pm and immediately went to the Sexy Pool to find some friends. When we saw the raucous crowd in the pool, and the shenanigans going on, we looked at each other and laughed, saying, "Holy sh!t, is that really what we're like?" Playing catch up was a challenge.
The tours do sound like fun and we usually like to explore around the places we go and not just spend the entire time at the resort, but TTR is probably the exception.
Yep, this place is where/why the term FOMO originated. "Dude, you should have asked her name. Now she'll be known forever as Miss D'opportunity." (reverse genders as you see fit)