This is my take on elves for my Greyhawk campaign:
Elves are one of the oldest folk living in the Flanaess. They have existed there throughout known time, ever since their creation by Corellon Larethian, patron of the Elves and Father of the Elven pantheon.
In the days before the great migrations of Suel, Oerid, and Baklunish peoples from the west, the elves lived throughout the Flanaess, on plain as well as in forest. The human people, the Flan, lived in peace with the elves, existing at the periphery of the elven communities and nations. But even then, the semi-nomadic Flan were a rising people, growing in culture as well as in number.
In those days, there were several clans or groupings of elves. There were the Gold elves, mighty in fighting prowess and vigor, the Silver elves, strong in knowledge and intellect, the Sylvan elves, strong in limb and dwellers of the forests, the Drow elves, masters of the arcane arts and insatiable in curiosity, the High elves, fleet of foot and open of heart, the Sea Elves, living under the waves, and finally, the Grugach elves, friends of beasts and the wild country. The clans existed in harmony and mutual cooperation.
While elves may have gotten along with the Flan as well as the halflings and gnomes, there were other races with whom they fought tenaciously. These were the goblins and gnolls and other humanoids, but most particularly the orcs. The orcs of the Flanaess were almost polar opposites of the elves, cruel, rapacious, and violent. Orcs hated elves passionately, supposedly because of some conflict between the chief elven god and the chief god of the orcs, the one-eyed Gruumsh. They tried to war constantly on the mighty elves, caring little for their own losses and tragedies.
In the midst of these wars with the humanoids, evil slipped into the elven realms. The arcane studies of the Drow had gotten them in contact with the Queen of Spiders, a mistress powerful in the magical arts, who seduced them with offers of power and knowledge, capturing them within her webs of deceit. By the time the other elven clans took notice, the Drow were already making their bid for dominance over the other elves. This is known as the Sundering, or alternatively as the Kin-Slaying. In a great struggle, the clans fought to first expunge the evil that had seduced the Drow, then to control them, and finally, to destroy them in a final effort to save all of elvenkind. The clan of the Drow was obliterated, but so were the Gold elves who had formed the nucleus and front line of the opposition against the Drow. The Grugach were severely reduced to a few families and all of the rest of the clans were scarred. Acrimony rose between the remaining clans over the conduct of the war and its consequences, damaging relations between them. The Silver elves, tarnished by the events of the war, were to become known as the Grey elves. The Sea elves retreated to their watery depths. The Sylvan elves insulated themselves within the deep forests. The Grugach barely clung to existence, hiding in the most remote of wildlands. Even the High elves turned inward.
The damage wrought by the Sundering caused the elven domains to retreat to the forests where their strength remained, leaving the plains to the Flan. Not long after that, the great migrations pushed whatever elves remained beyond the forest reaches into the woodlands.
The elves today have recovered a great deal from the Sundering. Although those events happened many generations ago, their legacy lives on. The Sylvan elves still cling to relative isolation, even among other elves. The High elves have again become the most open of the elven folk. The Sea elves have again emerged from the ocean depths. The Greys are also insular like the Sylvans, but they isolate themselves within their ivory towers of knowledge rather than deep forest homes. The Grugach are encountered only on rare occasion. The harmony and cooperation between the clans is not as strong as it once was.
There are some social characteristics most elves share, despite clan differences. Most elves are individualists, relishing their freedoms. They are also generally charitable, helpful, compassionate, and merciful. Many are also reclusive, proud, and patient (they live long enough to take a very long view). Elves love good entertainment and enjoy taking part in dancing, singing, telling stories, and drinking and eating find foods and wines.
Most elves also despise spiders of all sorts, keeping their homes clear of spiders and their webs. It is an old sentiment from the Kin-Slaying that spiders are the spies of the seductress. Giant varieties of spiders are always exterminated when found within elven domains.
That's what elves and PCs knowledgeable about elves know. What they don't know is that the Drow survived undergound, pale and leeched of nearly all pigment, and still under the sway of the Queen of Spiders. They also don't know that remnants of the Gold elves survived and are now the servants of the Valley of the Mage (as valley elves).