I am very enamored of the down-and-dirty, low fantasy feel evoked by the LBBs and S&W WhiteBox. At the same time, I freely admit that I love Supplement I: Greyhawk, and S&W Complete (which incorporates much of that tome in addition to various bits of Supplements II & III).
One of the things I love most about the LBB's and WB are the bare-bones spell list. To me, nothing screams "High Fantasy" quite as loudly as high-level wizards tossing around reality-warping spells like Reverse Gravity, Summon Demon, Mass Charm, Meteor Swarm, and, of course, Wish. One of the things I love most about Greyhawk, and S&W Complete, is that it includes those spells. Dichotomy, thy name is mine. Welcome to my world.
Anyway, I want a way to include such high fantasy tropes without turning my game into high fantasy. So, I had this idea. All the spells, as well as magic items, in the LBBs/WB are more normally available. The magic items are still uncommon, some even rare. The spells and items from the supplements are the subjects of specific quests to find them. If your magic-user wants a spell to stop time, he will have to do research, not on the spell itself, but on the finished spell as written by some ancient, powerful magic-user. If your paladin wants a holy sword, it will come at the end of some epic quest.
I can hear you now, "So what? This kind of stuff is common business with any good referee", and you're right. I'm proposing something slightly different than the norm, though.
Since spells above 6th level for magic-users (5th for clerics) and certain magic items have the capacity to alter reality and change the world, those seeking them should be subject to change, too. It is a common theme that those seeking power are not only changed by the power, they are even more changed by the quest for power. Literature if replete with stories of heroes sacrificing their humanity, health, sanity, and their very souls in their quest for power. That power can take many forms and need not be inherently selfish in nature. But the desire, need, and effort for it require a heroic effort to attain.
There should not be Vorpal Blades in a simple treasure hoard, even if it is an ancient red dragon. A wizard shouldn't find a scroll with Delayed Blast Fireball among the other scraps of parchment in a lost library. These things should be the object of epic quests. The kind of quest that regularly causes the character to make tough decisions and sacrifices. The kind of quest that routinely begs the question "Is it worth (this sacrifice)?", until the character has come too far and given up too much to turn back. It is at that most beautiful moment, when the character becomes resigned to the Fate his choices have laid for him, at that perfect moment of clarity, that epic heroes are born.