I've been thinking about Noism's excellent post about non-banal D&D. The gist is that many of DnD's rules and systematization make otherwise interesting concepts, like monsters and magic, mundane.
DnD magic is already said to be "Vancian". Nevertheless, while reading Vance's, Dying Earth and Eyes of the Overworld, I had a few ideas how to un-banalize DnD magic:
1) Spell Rarity
No one, or at least very few magic users, still have the knowledge required to come up with new spells. Magic spells are found in written form--players don't choose a new spell when they level, and their single initial spell is determined randomly by the DM.
Non-Banal Because: This means that the magic users will need to actively seek out new spells, often times from powerful magic users who guard their knowledge carefully. Similarly, magic users will have to guard their spells carefully. Ultimately makes spells a more valuable and exotic resource.
2) Learning Spell Difficulty
Anyone who wants to memorize a spell for the first time must roll a die to see if they succeed in an hour's time. Chance of success is a function of intelligence, spellcaster level, spell level. They can retry for as many hours as they want, but the chance of success is halved each time(rounding down).
Non-Banal Because: it gives magic more flexibility and less predictability
3) Memorization Limit
The number of spells that can be memorized at one time are the same as DND rules. Characters without spellcaster levels can only memorize a single first level spell. This number can be exceeded, with a chance of going insane.
Non-Banal Because: it gives magic more flexibility and less predictability. Allows players to take chances.
4) Spell Failure
Even once the spell is memorized, there is a chance of failure when using it. This chance is also a function of intelligence, spellcaster level, spell level.
Non-Banal Because: it gives magic less predictability. Spellcasters will be more careful about how they use their spells.
6) Some spells require components.
Non-Banal Because: these spells cost more than the user's time. They may have to seek components from far/dangerous places.
7) Allure of the Unknown
DM shouldn't introduce well-known spells, or when he does, rename them something exotic.
Non-Banal Because: magic is not a closed, well-understood system