Yaxchilan is definitely worth the effort of going there. I went on a small tour of ten people -- even though I loathe tours, I was glad to have used a tour guide in the end due to the three checkpoints you pass through where I saw many cars being searched -- booked through Palenque at our hotel. It does not matter which tour operator you use, although the prices may be different, but they will put you all into one van in the end. I paid $80 USD although I know I could have gotten it for less, I liked the tour operator I found, and he was at my hotel. He spoke perfect English and was very good overall.
This trip is not for anyone who is not in good physical condition. You don't have to be an athlete, but you will be in the sun, walking, and driving bumpy roads at times. I am in my late 30's, relatively fit with a ton of energy, and went with my teenage son during the off-season.
We were picked up at 6 am from Palenque and then picked up the others at their hotels. The driver was ferocious at first, and I was truly terrified of how fast he was going, although I now realize he was trying to get us there and back in time, nothing more and nothing less, and was an excellent driver. Still, the man drove fast and cut it close with some of his overtaking. My son got severe car sickness from it all, so I gave him motion sickness medication that I had on me. It was about a two hour drive until we stopped for breakfast at a place that was pretty delicious, actually, buffet style. Then, back in the car, off to Frontera Corozol, you have three lunch options that you pick prior to returning which are chicken, carne, or quesadillas. Don't lose your group because there's no one to really tell you where to go, especially if you don't speak Spanish!
Now off to the boat. This part is wonderful and very fun with outstanding scenery as the foliage grows denser, the border of Guatemala just 20 meters from the lancha boat, a long motorized canoe with palapa-covered seats on each side. It's also rather a long ride of an hour. The boat operator said nothing the entire time. I looked for crocodiles but saw none, but I did see many monkeys. When we arrived, we were given two hours, which was barely enough time! The restrooms are at the entrance and are clean, but be sure you have a good pack with plenty of water. And be sure you have a map. I brought the one from my Moon Guide, which was somewhat helpful although incomplete. We first went to the right up the steep path only to be greeted by howler monkeys and a large building which we climbed through a bit. This was rugged terrain. I saw one woman fall, tripping on tree roots. Then we descended back to the main site where we could not figure out how to enter other than through the aptly named labyrinth, which was pitch black, and where I walked through a fair amount of water. Fortunately for everyone behind me, I had a flashlight since everyone was wandering through the dark! It still takes a bit to get out, but it's an incredible experience. Not recommended if you're scared of bats; there are hundreds of them inside.
Once out, it's surprisingly large. Perhaps half the size of Palenque, although with few tall structures. The one tall one, the one that is the most famous, is an incredibly high walk. It's also slippery, or was when we were there since it had been raining for a few days, so be careful. We climbed this, but you cannot go inside. Then we climbed back down, explored the small structures, watched incredible leaf cutter ants, reveled at the rainforest since it's very thick here, although they do cut it back around the main ruins. Don't miss your boat back! Make sure to note what time you depart and how long they tell you you that you have to return. I am not sure what happens if you miss the boat or how they would even find you given that it's not a small place. Note: they give you this info in Spanish ;) I don't speak Spanish but recognized the numbers and such. I must say, it was the most stunning thing I saw in Mexico, and Mexico is a place where you turn the corner only to find something yet more stunning than you can imagine. This was one of a half dozen ruins that I saw and was my favorite (although Palenque's ruins are a very close second as they are far more grand).
Afterwards, you return by lancha to Frontera Corazol and have a sit down lunch which is okay, a bit quick, and Lacandon vendors will hawk their wares outside (I bought some bracelets for twenty pesos). Next up is usually Bonampak, although I will not review that here since this is Yaxchilan. It is usually included in tours, however. Then home, the driver a bit more relaxed, and you're dropped off at your hotel 13-14 hours later.
Things you will be glad you brought (in a waterproof backpack):
~ bug spray with a HIGH concentration of DEET (25%+) and still, expect to be bitten as you sweat it off
~ wear long pants and socks to minimize mosquito bites, as well as hiking shoes, not sandals, and a t-shirt, not a tank top. A hat (if you are going to Bonampak, which is not shaded). Lightweight socks and some sort of sneakers with tread on them. I wore a pair of regular sneakers and was fine, although they got very muddy.
~ your camera, of course, in a plastic ziplock bag.
~ a small flashlight
~ sunscreen (if you are going to Bonampak)
~ a lot of water. I also tucked in a few Cliff bars.
~ a map of Yaxchilan
~ a little money for souvenirs. While I'm almost morally opposed to purchasing trinkets, the Lacandon natives' jewelry is beautiful and authentic, made by them, and it helps them to sustain their lives, so I bought two bracelets and two necklaces, and I've worn all of these. They cost about 150 pesos in total and are one of the four things I bought while in Mexico for over two weeks. Also, drinks are available in a few places but not too many.
~ tissue pack, for the restrooms, as well as for wiping the sweat from your brow (I was glad I remembered this and used the whole pack)
~ antibacterial wet wipes. I use these not just to sanitize my hands but also to cool my face when sweating (did I mention it's hot? And humid?)
~ waterproof sunscreen. You will definitely sweat yours off and will need to reapply.
~ motion sickness medication if you are at all susceptible to it, for driving OR the boat, which is pretty still, although on return, a storm was kicking up and created some waves.
~ a pocket Spanish-English phrase book if you don't speak Spanish. Sorry, but this saved me when my son was carsick since I was able to ask the driver if he could sit up front, which was arranged. It also helped me in general since really, no one spoke English; the driver, they will tell you, speaks English. Ours spoke perhaps ten words?
While that sounds like a lot, it really wasn't, and I used everything there. I also brought a bandana to tie around my neck once it was totally sunburnt, which was at Bonampak.
Yaxchilan is amazing. It's a once in a lifetime experience and is stunningly beautiful. It's not hard although I did hear one person on the tour remark that it was the most adventurous thing she had ever done. I've done yet more adventurous things, but it was definitely not for the faint of heart but for those with a thirst for life. Wonderful!