I like what you are doing here.
In interests of my Elemental Paladin project though, I wonder if you could also do some small/lesser elementals short on the hit dice, that possibly could be pulled in with low level Summon Monster.
I do mean it, like what you're doing. Gives them some flavor. You accomplished your primary objectives. Going to run a few of these in game when my party gets to the point where they could reasonably tackle them.