mellowvision

I would probably lean toward running the waterfall with a filter rather than a pump, and would use an external cannister like the Tom Mini Rapids... or an internal filter like a duetto, that is small enough to conceal inside the waterfall, with the lid at the top, so you don't have to disturb anything underwater to clean the filter. for instance, you could use a half round of cork tube to conceal the filter, and use a spraybar or hose to create your waterfall flow.

I also agree about no splashing, water on the glass really distracts from the view. mosses and plants growing on the waterfall should help a lot with splash absorption, but careful planning is key.

You should also consider heating before you build... if you go the cannister route you can use a nice hydor inline heater, or with an internal, you could possibly conceal the heater as well, if you give it enough breathing room. honestly, if you're doing a local palu, you may only need heat in the winter...

which brings up another thing to keep in mind... I'm not sure where you live, but chances are it's somewhere that has a distinct winter period... many of the plants and mosses you'll find locally aren't going to keep going year round without a break. Here in NY, the terrestrial mosses I've collected locally all pretty much dry up or die off over the winter INDOORS, but out in the yard they keep green in the colder temps.