From what I've seen, a floating habitat about 50 km above the surface of Venus is feasible--the atmosphere is dense enough that breathable air is a lifting gas, and that would be about the height for earth-type pressure.
On the downside, the air of Venus itself is unbreathable, consisting of carbon dioxide and sulfuric acid. What protections would both a floating structure and a human body need to survive the atmosphere? What kinds of coatings would survive the amount of sulfuric acid in the atmosphere at that level?
In addition to a respirator with a supply of air, how substantial of a protection suit would a human need to operate outside for any length of time?
I am aware of the existing question about the feasibility of floating cities on Venus. I am focusing on the question of what materials would be useful for protection of both structures and human bodies, which that question does not address.