I have been thinking about this, and it came to me that elementals could have a kind of an ecology, sort of like terrestrial creatures and humans.
So at the bottom end, you have the fixed-INT elementals, just INT and POW, no CHA, and intelligence the equivalent of cats, dogs, lions or elephants. And the temperaments of the same - trackers, pouncers, even trappers like spiders (a ferocious trapper earth elemental could behave like a colossal antlion and lay a pit trap, waiting patiently for an enemy to walk overhead and then just liquefy the ground beneath their feet, turning what looked like solid ground into instant quicksand ...).
But the size of the creature is always determined by the amount of element conjured - a physically large elemental with a low fixed-INT would be an elemental beast of burden, and could range in size and capabilities from the equivalent of pony size to elephant size easily, depending on the conjurer's needs and the amount of material available for the summoning.
And then you have the variable-INT elementals. These are the ones whose INT is, like the sentient monsters, determined with a die roll. They have INT, POW and CHA, and their size (and POW) is determined by the amount of material available for the summoning.
Dull-witted ones (INT and CHA in the 1d6+6 range) would probably be servile, fawning things with little initiative; the ones with more moderate intelligence (INT and CHA in the 2d6+6 range, comparable to player characters) would have more arcane knowledge and even be willing to trade, but they would have their own agendas; and the most powerful and subtle ones (INT and CHA in the 3d6+6 range) would tend to seek to put their summoners in their thrall, suborning their summoners' agendas and replacing them with their own.
From what I read of elemental spirits, of the type summoned by shamans rather than the pure elementals summoned by sorcerers and the like, some elemental spirits' properties leach out through their binding objects - I immediately thought of summoning fire elemental spirits, then stuffing them inside palm-sized binding enchantments made of ceramic and metal. Instant permanent hand warmers. Just don't break them anywhere near stockpiles of inflammable fuel.