this is an awsome project! i would suggest frogs for the above water part.. but you said it would be all open so that probably isnt a great idea...
also the wall seems to just stop at one point, will it go up to the top or will pothos and creepers and vines just go up on their own to hide the obvious gap?.
for plants i would love to see a lot of bromiliads and things like you have listed. they will look really cool, for the underwater, why not go with some floaters as well like lillypads and red root floaters and things like that.
for inhabitants... do something that most people normally cant. something big. or a ton of small fish like german blue rams +angles or something. maybe altums?
you sure do like big tanks and projects!
- fish newb -
ohh and that backdrop is amazing! have you seen the ones people use for dart frogs? if not..
Dendroboard - Your source for dart frog information. maybe the people over there will have ideas for you as well?