Warning: Long Post.
It's called "Ultimate Magic" but so far the focus seems to be on Arcane magic, Sorcerers and Wizards. I'd like to see much more Cleric/Druid/Paladin/Ranger content.
More Ranger/Paladin bond abilities, or the ability to use their magic to boost their class abilities (favored enemy/terrain, lay on hands, etc) instead of casting spells.
An alternate class feature replacing Channel Energy. Or, more ways to get uses out of Channel Energy like Divine Feats used to. Maybe this isn't as relevant with domain daily-use powers, I dunno.
An alternate Wild Shape feature like the "Aspects of Nature" in Unearthed Arcana.
I like the idea of boosting the 3+Int/Wis/Cha sp abilities, but I think a reserve feat would be kind of doing too much of the same thing. Maybe, an alternate class feature or a feat that lets a caster sacrifice a daily slot or two to power-up their daily abilities, so a 3rd-level slot sacrificed boosts the damage of a "fire bolt" by +3d6, or extends the duration of a "dazing touch" by 3 rounds. Automatically granting a bonus damage/effect based on a spell-prepared is like adding a whole new class feature for the price of a feat, which is way too much in my opinion.
Alternate Alchemist mutagens (a high level one that changes size or grants a subtype?), more ways for a Summoner to boost their eidolon and/or summoned creatures (create a feat tree out of the Augmented Summoning feat?), more hexes for Witches (patron-specific or familiar-specific hexes, like improved overland flight for hawks or a poison touch for snakes; a blur effect for the deception patron or a smite ability from the strength patron). Curse-specific Oracle mysteries, like a sight-beyond-sight divination themed Oracle mystery only available to clouded-sight Oracles, or a Planes-themed mystery for tongues Oracles. Necromancer abilities, maybe make a necromancy-themed summoner archtype that creates/summons undead and has an undead cohort/companion instead of an outsider, etc.
Magic in architecture, like from the 3.0 Stronghold Builder's supplement - a bier of resurrection found in the holy grand temple of a healing deity, a room in a wizard's tower with built-in protection from scrying.
Instead of Pact Magic or whatnot, maybe tweaking the method that sorcerers/wizards/clerics acquire their powers. Instead of a sorcerer having a bloodline, they might acquire pacts instead, that grants powers at certain costs, and pick a pact each time they would gain a bloodline feat/power instead. Clerics might form pacts with Angels or Devils or other outsiders, replacing their domains. Witches and Druids might do so with spirits, replacing some or all of their hexes/wild shape (respectively).
Rituals and other outside-of-combat magic is a good idea. Also, along the same lines, cooperative magic that lets casters delay/ready their actions and cast spells affecting the same area/target to boost effects; i.e., a cleric "aids another" on an enchanter casting Hold Person, increasing the save DC. A witch with the agility patron "aids another" on a sorcerer casting Haste, increasing the duration.
Other ways of increasing spell save DCs, durations, or caster levels, like unique/magic metamagic components or casting a spell in conjunction with using a wand/staff/scroll of the same spell, or even a class feature or spell where a caster takes damage or other effects to boost spellcasting (like the Oracle's "Borrow Fortune" spell, the Insane Focus supernatural ability of the Insanity subdomain, or the "vicious" magic weapon ability).
