java moss would look great growing from that waterfall.
if i am correct this thing is huge in comparison to most. about 3'3" x 16'3" x 19'6" high. this leaves plenty of room for just about anything. these dimensions suggest an arboreal species and tall plants. the downside is that it doesn't seem that your viewing area is as tall as your enclosure, so tall plants and arboreals will mostly get lost at the top.
i suggest adding some glass to the top to open up your viewing area and your options here as a dwarf palm / small tree and some retf's would be a great start and contrast to the normal teeny enclosures we see very often.
anubias would be a great little plant to fill in under your waterfall as it grows great in an emerged state! there are also versions of different size so it can be layered short to tall - front to back to provide plenty of hiding space. if done this way it will look like one large ascending plant eventually.
moss on wood provides a very natural look, and will soften the right side of your tank beautifully.
ivy is great and there are many kinds. since you decided not to go with an elaborate background you could easily give the illusion of more depth as well as hide your back wall while (species dependent) providing a starting point for climbing. you would just need to plant a climbing version in your substrate.
nepenthes (pitcher plants) and orchids are always a welcomed addition as they are very beautiful, colorful and tropical and give a good contrast to the other (filler plants). besides nepenthes are carnivorous...
a chinese water dragon would probably love your waterfall area and would be very happy in an enclosure that size but would probably need climbing apparatus to reach the top sections of said waterfall.
as for lighting, uvb is only necessary for some species and some common bulbs have been proven to be dangerous even fatal... so be careful.
here is a link i found on this site.
as for the plants there are many lighting options. i always say use what you got but you seem to have that covered already.
having said that, imo flourescent (compact or not) would probably be your best option. they will not create heat and use much less power than other options. this will reduce your lighting bill and make it easier to regulate temps.
they also make simple moonlights for aquariums out of led's. you can also string some up how you want them and use a dc power converter to power them if you are handy with electronics... diy links necessary here.
for a basking spot a ceramic heater will be your best bet. they last much much longer than the crappy bulbs they push at most pet stores that seem to last only a couple weeks. even if $ is not a major concern you will still regret all the extra trips to the pet store when basking lights continue to die one after another.
when looking for lights look for daylight, sunlight or best bet grow lights. these will help your plants grow to their maximum potential. wal-mart is your best friend here... sorry to say. mix and match for best results!
since you have experience and an abundance 5000 - 6500 kelvin works great also. once again mix and match attempting to cover full range (5000 - 6500).
because your tank is very large i would go with a commercial mister as opposed to manually or diy. mist king seems to have a good rep, look into it yourself to make a better decision.
i am personally considering plumbing in a self-sustaining reservoir including a reverse osmosis system w/carbon filtering and a toilet float to keep it full for a hands off approach and i am very surprised i have not seen one done anywhere. from what i see here, with your experience with ponds this should be right up your alley. oooooohhhhhhh the bragging rights you would earn if you could post a how to with pics when you are done, plus the ease of use would be unheard of... great for you!!!
r.o. systems are available at any hardware store and even wal-mart. they are not that expensive when compared to buying bottled water and can be plumbed in using a hose splitter, hose, and some adapters from your cold water feed to you washer or straight from your existing piping. the water would be very close to room temp at all times if your reservoir was just big enough (it wouldn't take much, keep it small to avoid several stagnant water issues/growths).
consider a temp regulator w/a probe and digital readout/settings to power all heating equipment except for basking lamps. w/this you also have the option of day/night temps to simulate nature better... healthier imo.
there are several ways to heat an enclosure and should be considered. your land, air and water should all be pretty constant. a uth (diy probably best here), will help w/land and back wall. an aquarium heater should be used in reservoir for waterfall. a basking light/ceramic heater should be used for air/basking... most herps will require these and they will be necessary for tropical simulation.
note: and an important one... i have not seen anything about a fan. this is very necessary if you want to see through the glass due to moisture, circulation of heat, and air in general. remember tropical means wet... wet means closed, closed means stagnant. insert diy link.
now all we need is some links/extra opinions on species, flora and fauna. then we can narrow down specifics once decisions start being made.
sorry, i do have links to everything i have mentioned saved on my pc, but it is down currently and i'm using the wife's p.o.s., so links will have to come from someone else as this is a lot to cover.