Luckily, Venus is quite windy. Extend some anchors with sails downward, some windmills upward and take advantage of different air layers. As for the cloud city falling, generally, that should be unlikely as no thing will be reliant on a single floatation device. Maybe you can even add some shutes to allow for plenty of recovery time. People really should be strapped on/ inside.
Maybe I'm just not good with
heights depths, but I just feel that this would be precarious. Maybe this means I'd find
any spaceflight unsuitable, and even re-entry down to solid (Martian, Ionian or whatever) ground a problem. OTOH, right now I
think I could handle freefall if I know that it's more "free" than "fall". (Now, would I work outside of a spinning station, knowing I might get flung off? I don't know. There's a good short SF story regarding that kind of situation, but I won't bore you with it now)
Mercury would require a driving base to stay in the twilight, or a ridiculous amount of heat shielding. Also, Venus the only nongasgiant (not counting earth) planet with a decent magnetic field.
Are you aware of the the solution that was used for the Mercury base as depicted near the end of KSR's R/G/B-Mars trilogy of books? A pretty neat solution, I think, though I won't spoilt if for you (even though it's not a
major plot point, just a passing location used for a few 'scenes' of action) It's within a nominally, if speculatively, Hard-SF framework with the "day after the day after tomorrow" kind of tech-level, but is actually far
less speculative a mechanism than the far bigger spoiler about genetics developments...
...combining the terraforming of Mars with "Areoforming" of Martian settlers bodies and of their offspring, for a "meet you half way" approach to making the place liveable and speed the process up for those so treated.