Complete beginner looking for recomendations

[tokyo]

Ok, that was annoying. I tried to preview my post and my entire message was erased. Oh well, hopefully I can remember it all.

I am a complete beginner to the orchid world. Until now I have been completely obsessed with my fish and aquariums, but an aquaponics project I'm working on has made me realize that there is alot more to the picture than just what goes on underwater.

So I am planning on setting up a paludarium and would like an orchid as the center piece. I would love some suggestions on what species I should go with.

The tank is going to be atleast 12" wide x 18" deep x 30" tall and no more that 12" wide x 21" deep x 48" tall. So it needs to be able to fit within these dimensions.

I would like someting that will grow on the wall or a piece of wood if at all possible.

It should be good in humid tropical conditions.

Also, no hybrids please. Just a "pet peeve" of mine.

Something from South America would be great.

Thanks!