It was a significant additional expense to get to this site and a lot more driving, but it was wonderful and with the effort.
Its peak was in the 7th century AD and it wasn't inhabited for over 1000 years which means the jungle had completely taken over. They've only excavated a tiny percentage of the site, as is the case with many of Mexico's sites, but it's easy to start with the biggest mounds and find amazing things.
We'd read that you needed an entire day for this site, and I'm sure you could spend that long, but we thought the 4-5 hours we spent there were good. It's fairly isolated anyway so I hope you wouldn't try to just stop by for an hour or two on your way someone else. This is a destination.
One thing I didn't know about the site is that there is a truly lovely waterfall below it where there are a few excavated ruins. It was lovely to sit there with the water rushing everywhere, in the jungle, amongst the ruins.
Some of the best finds from this site are in the Anthropology Museum in Mexico DF. It was nice to see the real site after visiting the museum so many times.
We parked down next to the museum (rather than driving up to the ruins and parking there). There are two paths up to the ruins and you can take one up and the other back. It's worth going to the museum and on both paths, especially since you get to enjoy the waterfall.
It was raining gently most of the time we were there. It was very quiet and there were a reasonable number of tourists but it certainly didn't feel at all crowded.