Just noted that according to their description earth elementals look like the material from which they're conjured, which I guess is pretty cool. The only problem: what happens when you try to summon one on a ship, or up in the air?
Small Earth Elemental
Smalls aren't that bad, to be honest. Their speed sucks, but their ability adjustments are fairly nice (also atypical for a small creature). Earth Mastery is pretty useful at low levels, then becomes a horrible liability as everything gets a fly speed.
Push is basically a watered-down version of Improved Bull Rush... which will be near-useless on a small creature. Also, bull rushing just isn't that strong.
More interesting is Earth Glide. It's a very potent exploration tool, getting the elemental past about everything except for metal-lined walls.
In the end, I'm going to refrain from assigning a positive LA here. Small earth elementals pretty much only have Earth Glide going for them, which while nice isn't enough to make them a viable choice. Remember: any druid can just get a small earth elemental companion and have it scout. +0 LA.
Medium Earth Elemental
Again, no positive LA. The strength score is swanky, but a well-built mineral warrior is surpassing you in most ways by now. -0 LA.
Large Earth Elemental
8 RHD should be a pretty good deterrent. -0 LA.
Huge Earth Elemental
The party caster has been able to summon those for a few levels now. Pass.
Greater Earth Elemental
Justifying my assignments is overrated! -0 LA for you!
Elder Earth Elemental
I like your alliteration, have -0 LA.