Funny enough, I would have assumed that the intense gravity of a gas giant would have caused the PSI measures to increase much more sharply than on earth; resulting in a earth-like pressure band only a few hundred meters thick.
Turns out the 'surface'(edge of the atmosphere) gravity of gas giants isn't intense to begin with. Jupiter is the only one with noticeably higher gravity at 24.8m/s2(2.5g), pretty weak considering it's 300 times more massive than earth. The others, Saturn Uranus and Neptune, have barely more surface gravity than earth. Hell, Uranus has less at 8.7m/s2(0.9g). Partly due to the surface being so far away from the superdense core.
This has interesting implications. First of, the earth-like pressure band is here and healthy, probably even thicker. Secondly I had assumed a crew of a gas-giant-airship would be at best reduced crawling around on the floor if they didn't get flat out crushed. Well nope, they'd be perfectly fine. No need for artificial gravity, or anti-gravity for that matter. It'd be just like walking on earth.