Go to a Jungle Lodge
Iquitos is the place to book various jungle lodges, which will allow you to stay in the Amazon and see the jungle close up. There are various lodges to choose from. The more luxury choices are the Explorama lodges, which have the canopy tour and I think one of them even has a water slide. We went with the Muyuna Lodge mainly because its office was across the street from where we were drinking (right next to the main square -- most the other lodge offices are in a different part of town), and because one of the locals we were drinking with said it was pretty good. I got the feeling that Muyuna was a more... granola... lodge than others, what with the kumbaya guitars in the "lobby" cabin, the optional vegetarian fare and the big group of hippies on an ayahuasca trip. The location is excellent -- all the cabins are on a raised platform and the river comes up over the ground in the high season. No electricity, FYI -- the place is lit by lanterns an candles, and good luck keeping secrets as are the walls are basically mosquito nets. Fun fact -- I'm pretty sure that dude from Travel Sick went to the Muyuna lodge as when I saw the Peru episode I was totally like "I know that blue chair!!" My only beef was the main guide didn't really give us much information on what to do (He assumed we knew how to dress for the jungle and how to put on mud boots, etc. Then, when us city kids were all like "huh?" he went off with the two more experienced lodgers because we were too slow).
There are lots of other options, as you will see when you get to the airport as people will try to steer you toward different lodges. The further away you get, the more untouched the jungle is and the more wildlife you will see.
The lodges run about $100 a day, which is pricey, but the jungle is so awesome. Included in the price is a guide, meals and 2-3 activities a day like pirahna fishing, visiting a village, a walk through the jungle and evening wildelife spotting on the river.