As it turns out, Flame Atronach, Frost Atronach, and Storm Atronach are actually glitched. They gives far less XP than they should because of an oversight in how their spell profile gives XP. Unlike any other spell in the game the Atronach spells have two instances of input which BOTH contribute to the magicka total of the spell. Usually a spell with have other affects inside the spell to activate when you have a perk. For the atronach spell this affect is their stronger counterpart that's added by Elemental Potency. The extra instance of affect in every Atronach spell both have magicka requirements that add to the total cost, but the XP you gain is based on the magicka cost of only 1 of the affects.
So while every other conjuration spell in the game (Boneman, Seeker) give XP based on their total magicka, the Atronachs only get half.
This mod corrects this by simply changing the XP multiplier to give XP based on the single instance of affect to match the spell's counterparts.
Oh, and Raise Zombies? It's set to give WAY more XP than any other conjuration spell. Although this may be intentional, this mod balances it out.
Also, I added Boneman to the level lists so you can buy it starting at level 1!