I think you have some great ideas. I really like the look of scapes like the ones you've shown as your inspiration.
I agree that you want to be sure your plantings don't obscure the rocks too much. Rocks have a way of shrinking once the tank is fully planted! Even low carpeting plants like HC have a way of hiding the rocks more than you expect, especially in a small tank. You may need to go with larger rocks than you think you need.
Also, it has been my experience that the substrate tends to flatten out over time, so that nice slope you've shown may not last. I try to use rock placement to reinforce the slope (this can also slow down hairgrass from completely taking over). That's sort of what I did with this tank, although eventually it did flatten out. This is a 2.5 gallon tank, and when I first put the rocks in, they looked huge!