I tend to agree on the danger of using cattails after seeing how they affect the large natural pond down the road from me; very hard to get rid of, grow prolifically and very dense. I didn't even want to take a chance using the minis, though they should be easier. I'd put the cattails anyplace they could NOT spread easily and someplace you can even more easily dig up.
For a couple of your spaces on the shadier side, I'd recommend hosta as there is a very large variety and the foliage is there all summer. Some get large, some stay small. You have choices.
For the above reason, and esthetically, I'd not plant anything directly in front of the water fall, but to the side. I have some horsetail rush planted this way. You can google. Also, because I didn't want to worry about runaway rushes, I put the pot in a plastic bucket so the roots are contained, though so far, they don't seem to be that aggressive. So, horsetail rush is another 'medium-tall' choice for near the falls.
For your red zones, the partially submerged, I might suggest parrot's feather or sensitive plant. Both will creep out over the water, if allowed by either you or any fish. Last year, the fish(or snails) seemed to curtail much of my parrot's feather roaming by nibbling on the roots. Parrot's feather would still allow you to see the water and any fish. Also, I have water clover which stays on the surface or rises up to 4" above. It can be more dense but like the parrot's feather, the fish tend to nibble on it. Still, the water clover has a good growth rate.
Another red zone idea might be a fairy lily; stays low, gets nice flowers.
For the sun embankment areas; a suggestion (wife induced, btw!) is to plant Asian lilies. Nice flowers, perennial, compact until they eventually spread out. Also, carpet juniper is nice as it stays low, has bluish tinge to the foliage. Another idea for the sunny areas is peony; they don't get too tall, have a different textured look to their leaves and nice flowers in spring.
Anyway, some ideas.
Hope it stirs the thought process!
Michael
