I like your choice of river rocks. They are much rounder than what I have chosen which are the more flat and oval shaped ones. But my plecos like to be on the underside of rocks and slate, so I go for flat.
Every time I look at one of your pics I am jealous. I have yet to see one of your tanks that did not look really nice. I firmly believe that aquascaping is an an art. One can only do it naturally, one cannot learn to do it. One can learn techniques, but that is not the creative part. The ability to see the finished product in your head before you even start is a rare talent. So is making it happen. Of course this includes the choice of fish and any inverts.
For me the best aquascapes are the ones which have that "haphazardly" natural look but have actually been specifically designed to look that way. (While I recognized his skill, I was never a gaga fan of Takashi's tanks despite acknowledging his contribution to aquascaping and for the plants to which he introduced us.)
I'm definitely more of a fan of the natural looks. I like biotope scapes, or ones that are less than polished... not the biggest fan of things like iwagumi or Dutch. They can be well done but they're not my taste or style. Iwagumi especially as the scapes don't benefit the fish as theyre too open and not enough shelter for fish. I like scapes that suit the fish's needs most.
And I try to use that with my own scapes. I try to factor in what the stock prefers for their homes, but I also like to enjoy the look of it too. Ex, my one 55g that houses my Farlowella cats has a lot of spindly branches involved with the structure holding the anubias in it, to factor in that they live mostly on these branches, and need enough to support all 3 in there for grazing and shelter. Same time there are two Ancistrus bodenhameri that benefit from the driftwood caves the structures create too.
My other 55g has more dense plants, as the fish in there appreciate the planted jungle.
This tank, the 135, i kept the hardscape larger, and went more minimal so I didn't take up swim space as the fish grew since goldfish aren't exactly small fish... while same time offering them shelter, places to rest or explore, things to do because they're quite curious and busy fish. Sand substrate because they go nuts digging in the sand. They love it even if it gets all over the place. It's their home before it is my own visual artwork. So fish needs have to come first when I put the scapes together.
As for the rocks, I have a local river I collect my stuff from, and I have a weight limit on my floors... old building and I live on the 2nd floor, so I had to be mindful of weight. Could do less larger rocks thatd be noticeable, or smaller ones that wouldn't stand out as much. Most of the good sized rocks I wanted were rounder. I'd love to do more rocks, make it look more like a stream, but I worry about the weight limit and going over it. A 6 foot tank is a loooot of weight as it is.
As mentioned in previous post to this, I am anticipating a rehome from a friend so will need to add a structure suitable for the fish. May need to pick up or search for a suitable cave that looks natural as well.