"And cover most of one's head. :^) Perhaps it is very noisy inside the space colony, like a mall which it resembles."

In order to make something like that colony, space dirt would need to be somewhere around $200 per ton- or 5 cents per lb. Or about 20 times more expensive than on earth.
{Large boulders as "pleasing elements in the landscape" could be as cheap as on earth [assuming one has to move them around on earth]- and such things as the Pyramid could be cheaper to make in space as compared to Earth. Stone structures on Earth are expensive to make, and they would be expensive to make in space- but there could be less difference in cost in space as compared on Earth. So, lavish design in space could include stone replicas of earth's ancient building or monuments.}

So, to have the refined things such as steel structural members at cheap enough price to do it economically, one will also have raw material fairly cheap.
Therefore with cheap dirt, bricks, or stone it's quite possible these things would be used a lot in the space colony- unlike ISS.

So using a lot space dirt and having trees, etc will dampen sound, therefore including other factors, space colonies could be quite serene- unless someone brings in a lot parrots or something.

"I well remember those space colonies floating at the Lagrange points. I also remember being promised men on Mars in the 1980s and lunar colonies by 2000."

As a metric, I think that when one has electrical power in space which one can buy at a cheaper price than you can buy electrical power on earth, then you will have such thing as large numbers of people living in space being possible- large numbers meaning more than a million people living in space.
And then, at that point, it could take more than a decade to build such things as a large space colony at L-5.
Some people think it's possible to create electrical power in space at a lower price than on earth in less than one decade. I don't believe it is possible.
I think it would take a couple decades even if we were very smart, and optimistically, probably it would take few decades to do this.

"Now we can't even commit to more than some extended stays on the Moon in the 2020s and I have the feeling I will be a very old man by the time humans go to Mars.

I too wish we would focus on utilizing NEOs. "

It seems to me the being committed to more extended stay on the Moon, will result in taking longer to send crew to Mars.

What is important in this regard as far as NASA activity, is finding something which is minable in space. Period, end of story.

Unless you have visions of NASA's budget going north of a trillion dollar per year- it can't do the kind of things you want to see.
It couldn't actually do it even with a +trillion dollar yearly budget, but at least it's vaguely plausible.

What is minable in space is water.
I know of no other thing in space which is minable.
Once you can mine water- everything in space becomes minable.
Including bringing PGMs mined on the Moon and/or NEOs to Earth.

And nothing in space is minable if NASA is doing the mining.