Where it's posted shouldn't really effect the replies, but I went ahead and moved it to real world travel since it probably fits better there.

I don't have any direct experience, but I was speaking to someone recently who will be attending Arkana which is rated #1 on ayaadvisors.

We also watched She is a Shaman recently, a documentary about the Ayamadre retreat in Iquitos.

I've also had my eye on The Rainforest Healing Center for master plant dietas.

I can't personally vouch for any of these, but they are the ones currently on my radar.

There are a couple older threads on the forum here and here as well.