I like your plant selection and think that they could look great with those rocks.
I confess I am not fully enamored with your rock placement though, especially the big one. Play around with that guy some more; try on its side so the rounded face echoes the front of the tank, try it on the small end, the long edge down, put another on top of it, anything that occurs to you. But right now it looks like it got plopped in there and landed weird.
If you like the scapes you linked to, notice that their rocks form a composition of some kind. Yours could be one tallish jumble like a mountain, or arranged large to small like a hillside, or any number of things.
Hardscape is important. Consider playing around with various combinations on a piece of cardboard the size and shape of the tank bottom (easier to move around). When you find a look you like, leave it there overnight and look again the next day.