Well, there aren't a lot of decent subjects that start with Q, so I sort of cheated and picked this one. To start, my ideas of elemental planes, and alternative planes of existence in general, were formed by the last few pages of the AD&D player's handbook. I'm sure this is the case for quite a few gamers in my age group. Air, earth, water, fire...these made perfect sense, as they are the classical Greek elements. Then the Manual of the Planes comes out and throws a monkey wrench into the whole affair with all these other elements that seemingly made no sense whatsoever. The para-elemental planes, those were somewhat plausible; but the quasi-elemental planes? Nonsense. Until we realize that, yes, these are actually part of the alchemical tradition. There's historical precedent for their existence, which proves once again playing D&D was like getting a Renaissance education under the guise of fun. As an aside, my love of classical music was in fact a direct result of Bugs Bunny cartoons, so there's certainly nothing wrong with it. Anyway, the planes themselves are described fairly well, but why would anyone ever adventure in such a place? Hmmm...
Basically it's like being in a perpetual thunderstorm with no rain. Continual lightning strikes mean eventual deafness and probably deadness because you have a 10% chance of being struck by lightning EACH ROUND. Yeesh. At least you can breathe in here. This one might be cool if you're a crazy wizard and build a tower on some chunk of earth that's floating around. Better put up some sort of way to keep out all the lightning, though.
Out of all the quasi-elemental planes, has got to suck the most. Breathing is nearly impossible, you can go blind easily, and there's literally nothing here but bright ass light. Hey, would you enjoy having an adventure on the Sun?
Now things are getting interesting. Solid ground, basically throughout. I imagine it would be possible to find tunnels and caverns, hiding possible settlements of weird, crystalline creatures. With a lot of prep and plenty of luck, this one is ripe for exploration.
Like being in a sauna. Not much else here besides slow moving inhabitants, and pretty boring. Just like a real sauna. The Manual of the Planes says that steam elementals resemble smoke elementals which essentially means they smell like cigarettes. Not hostile, but really annoying.
Rating: D+ for booooooring
A void with no air, but pressure and a decent temperature. How that works, I dunno. About as hostile as Radiance, but less fun. At least you won't go blind.
A cold, barren wasteland that sucks the warmth from the souls of living creatures, sort of like Ohio. Another possible playground for a crazy wizard, or maybe some weird cold creatures. This one has potential if the DM is creative.
This one is like ash, but has even less going for it. You just eventually turn into dust. For exploration, this place sucks, but as punishment, it ranks near the top. Drop off your hated foes here and laugh all the way to the tavern.
Resembles Minerals, but it sucks up moisture like there's no tomorrow. Again, with proper preparation, this could be pretty good. Weird salt creatures in a desert environment. I'm sure some enterprising individuals have dug out inhabitable areas and safe-guarded them against drying out. A little better than Minerals because it's easier to avoid dying of thirst than getting cut to ribbons whenever you take a step.