For the cost of the spell slot for the minor elementals you can get some very useful services in a more Role Playing heavy campain..
A small fire elemental summoned into your oven can ensure you don't burn your meals, and might earn you some extra cash as a cook in a high dollar inn. (Circumstance bonus to cooking skill checks)
A small earth elemental can scout for gems or mineral deposits underground without having to dig up half the mountain side looking for a good vein, and could earn you some extra cash from the local group of dwarves. (Better than a Locate Object to search for generic things like "Uncut Gems" or "gold", and it can possibly scout out the easiest way to dig up the treasures.)
A small earth elemental can also be valuable in searching for pit traps in a corridor or along a path as it can travel under the ground and find holes that might be covered with illusions or obscured from the top. (A little better than a detect traps spell in that the elemental can detect the pits, and set them off for you with relative safety.)
A small air elemental makes a cheap and effective vapor hood for the amature alchemist. Or can aid in getting rid of spells with vaporous effects like stinking cloud that can be dispursed by a gust of wind.
And my favorite use for minor elementals is...
Using a small water elemental to create a magical "Whirlpool" bath. Nothing soothes the aching bones after an adventure better than relaxing in a hot whirlpool bath.
CAM