How much space do you have to put a tree in. Thats vital in my answer because the best would be a huge tree but if your enclosure is only 6-10 feet tall then thats another story. I usually only use fake trees because sure real trees are badass, but when the time comes to change the cage it puts you in a hard situation. Also, for the humidity, A waterfall would look cool, but the plumming and maintainance would be insane. This would be easier and probably less expensive. http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=9738&cmpid=07csent&ref=3665&subref=AA&srccode=cii_9324560&cpncode=07-66723650-2

You can program it to you needs. Example: spray for 5 seconds every 2 minutes or so.