Moreover, if we are to consider possibilities beyond our current capabilities, why not focus on building space stations with artificial gravity instead? There would be no need to be tethered to Venus when we could exist without any attachment (although we would still be subject to gravity of other entities).

The main point against is that there is no reason for anyone to go there. Cloudtops on Venus are immensely resource-poor, most importantly in hydrogen. I agree with you that there is no advantage to a floating colony over a spinning one.

The one place on the solar system whose colonization is often ignored is Mercury. It has an extremely low axial tilt, meaning that all the craters on it's poles are permanently shadowed. It is also constantly bombarded by solar wind, which produces water (ionized hydrogen impacts oxide rocks, and binds to the oxygen). Then the water is a gas that bounces around until it impacts the bottom of a shadowed crater, which is cold enough to freeze it. Based on data from the MESSENGER mission, the south pole of Mercury alone has more water than all of Mars.

That's not really a point in favour compared to an orbiting spinhab. You only need it to float so that it doesn't fall to the ground. And you can achieve that by not leaving orbit in the first place.

A floating habitat would have less access to orbit, would have density / weight contraints and would have to deal with the corrosivity of the venusian clouds.

Those are very different engineering challenges. Separating similar pressure gas mixtures is question of porosity, but not force. Separating different pressures of the same gas mixture is not just a question of porosity, but you also need manage the forces created by the overall pressure differential.

Edit: If you take a helium balloon into space (or high enough in our atmosphere) it explodes rather than just slowly leaking and equalizing it's gas mixture with the atmosphere.

That will come in handy when we deconstruct Mercury to provide the raw materials for a Dyson swarm.

So, AIUI, it's easier to get to Alpha Centauri than to "fall into" the star we orbit.

Note that at sufficient height over Venus, air is buoyant, so quite a few designs for Venus assumes at least part of the habitation itself is within the structure of the blimps, and the pressure means leaks are much more manageable. You also get a "free" radiation shield on Venus thanks to the induced magnetic field, and that alone might well be enough to make it more attractive than a larger space station.

We don't know if a full Earth gravity is necessary for human health in the long term, or if we could get away with something less, like half a gee. And we don't know how small the centrifugal force gradient has to be between the feet and the head for people to be comfortable. It might turn out that we could just get used to it, like how people get over space-sickness, so a spinhab with a relatively small radius might be fine. All we know for sure is that prolonged exposure to zero gravity causes a gradual decay in bone and muscular strength.

There was a plan for the ISS to have a spinning module to study these questions but it never happened. It's a shame, that kind of experiment would be far more valuable than whatever public relations crap they're doing up there. I actually find it astounding that we haven't even tested long term partial-gravity on animals yet.

https://hackaday.com/2021/06/08/iss-artificial-gravity-study...

It would actually be easier than on Earth because on Venus atmospheric pressure increases like crazy as you get near the surface. So an habitat pressurized at 1 Earth atmosphere would naturally float in Venus' atmosphere like a submarine or whatnot floats in Earth's oceans.

My understanding is that at the relevant altitude in Venus' atmosphere the temperature would also be very Earth-like so no big heating/cooling issues, either. I have read some say that the upper atmosphere of Venus is actually the most human-friendly environment in the solar system outside of Earth.

It's actually not a far-fetched proposal.

But of course at the right height breathable air is also buoyant on Venus, and that's one of the key things that makes floating habitats attractive - we can use air for lift and live inside the balloons, and thanks to the equivalence of pressure small leaks shouldn't be an issue. Multiple compartments plus some spare, un-inflated sections, and you can have decent redundancy.

(I am planning a book set in part on Venus, but it's book 6 of a 6 book cycle and I'm currently being very slow about finishing book 3)

Plus makes emergency procedures for leaks MUCH cheaper - light emergency ponchos and masks, and just walk over to the next sealed building.

I'm assuming you mean sealed buildings inside the blimps here, because you'd have nowhere to walk to on the outside on account of being 50km above ground. In which case you probably wouldn't need anything in the case of a leak.