Though they may seem pretty rustic to those accustomed to Sheratons, Hiltons and the like, the rooms are at the Ariau are pretty impressive considering the location. Most rooms are equipped with refrigerators and bathrooms showers, and two of the towers have air-conditioning (WELL worth the extra US$25 per night). There are a few special suites with luxuries such as TVs, but they are much more expensive and, given how little time you spend awake in your room, they aren't worth the extra money.
Ariau is an amazing place: a sprawling complex of towers connected by walkways built entirely at the treetop canopy level. You'll see plenty of wildlife here. In fact, animals make themselves quite comfortable. Don't be surprised to find a monkey attempting to make off with your drink or a parrot nipping playfully at your feet.
There are three small pools to cool off in, an observatory, an air-conditioned meditation pyramid (it's too bizarre to describe, words cannot do it justice, you have to see it for yourself), a bar, a cyber-cafe(!), and a few stores where you can buy anything from souveneirs to drinks to gemstones.
Meals are served at set times in the dining area, a circular room filled with long picnic tables that has a very summer camp feel to it. It's not gourmet cuisine, but they do a pretty good job all things considered. Meals are included in the price, but drinks you have to pay for.
At the beginning of your stay, you are assigned a guide. Guides are assigned groups according to language. Guides will take you an various canoe trips including pirhana fishing, jungle trek nighttime alligator spotting, village, flooded forest, and early-morning sunrise. They're all excellent, bring plenty of film, and be sure to watch for river dolphins leaping out of the water in your canoe travels.