I think it would be good if you guys did a little something with the elementals.  They need a little spice.

Earth elemental is decent but could use something like a tunneling ability.  It could be a 1 turn timer that lets it tunnel to any spot on the battlefield.  And on the strategic map its move could drop to 1 and it could tunnel through mountains.

Air elemental could use haste, and it could have an auto-cast of obscuring fog.  Flying is nice.

Water elemantal has cold damage and slow which are good, but have it cross water.  Give it a cold shield and ranged damage.

Fire elemental has fire damage and the damage shield, but maybe let it cast fireball once a combat, and let it appear at the fireball target when the effect goes away.

Just a few thoughts to make them more desirable to summon.