Probably better to get some kind of cloud city working on Earth before attempting to go trans-solar-system with the concept.
That would indeed be part of the development process. It's harder on Earth, mind you - a Landis habitat has to be inflated with heliox on Earth, which is much more expensive and permeation-prone. But such a habitat absolutely can be tested on Earth.
By the altitude Venus' atmosphere is more dense than Earth's, it's also highly corrosive.
The sulfuric acid is quite overstated in the popular imagination. It's more like a bad smog (or more accurately, vog) - several to several dozen milligrams per cubic meter, as noted below (also as noted below, OSHA allows people to breathe up to 1mg/m^3 for an entire 8-hour shift). It's much more of a resource than a problem; design work would be simpler if it were denser, not sparser. Material compatibility is easier to ensure (via fluoropolymers) than the scrubber design aspects are; you have to have high mass flow rates because the sulfuric acid is so sparse.
(That said, there was some - disputed - evidence from Vega that there may sometimes be "rain" on Venus. If that's correct, that'd be quite the blessing for resource collection. It's sad how we don't even know such basics as "does it rain on Venus?" at present)
Jupiter is a little too active for my taste, but perhaps Neptune or Uranus might have some attractive latitudes at which to float a city, assuming you bring your own power sources and don't rely on the sun.
The gas and ice giants are tough. They're very, very far, exceedingly hard to get out of, and because they're predominantly hydrogen (80-96%), the Landis design is right out (you can't live in a spacious envelope, you're stuck in a gondola); the envelope has to be hot hydrogen (heated with a lot of energy, because you lose it quickly on those scales). The gas and ice giants also have the wrong ratios of temperature to pressure - too much pressure relative to temperature. Plus, much less diverse gaseous mineral resources, and (effectively) no surface mineral resources at all. And of course as you note, little light. Venus is far better in virtually every respect. Its right next door, the easiest planet to get to, a great location from an orbital dynamics perspective, and it has everything.