While most dark fantasy does focus on humans being alone in a hostile, dark world, some settings have made the standard races work in a darker sort of world.
For example, the D20 campaign setting Dark Legacies by Red Spire Press (
www.redspirepress.com). Its basically a future setting of Earth where the world was sent into Hell and has re-emerged a few millenia later after demons have scoured the Earth and new halfbreed races have developed (essentially elves, dwarves, etc). Its very well done and fabulously illustrated, and has a very dark gothic feel to it where humans have gained the upper hand and some hope for the first time in thousands of years. Its sort of S&S, combined with a post-apocalyptic feel.
My favorite dark fantasy setting that is published is Warhammer Fantasy Roleplay 2. The standard fantasy races exist (dwarves, elves, halflings) in a very humanocentric world at roughly the early Renniasance level. The non-human races are explored pretty thoroughly in the WH literature, and have very non-human mindsets (dwarves are primarily concerned with clan and family honor and bear grudges for thousands of years, elves are cold and aloof to humans to the point of detached cruelty sometimes, etc). Chaos is a constant threat in the Old World, both through the obvious (invasion of chaos hordes, beastmen), and from insidious internal threats (mutants and the perversion of chaos cults and dark pacts with the Ruinous Powers). Life is very hard and brutal for most people, and large areas of the world remain uncivilized. Someone once said WH is like starting out thinking you're playing D&D, but only later realizing its more Call of Cthulhu (except Chaos is more aware of humanity than creatures of the Cthulhu mythos are). I guess you might call it S&S with a healthy dose of intrigue and madness. Great stuff.
I've also run a homebrew dark fantasy campaign using AD&D/D&D rules for the last 15 years set shortly after humanity comes out of a dark ages. Its somewhat similar to midieval Europe circa 1100, with warring feudal lords and few national identities. Very little exists in the way of written records before the dark ages, and for some reason few people have any idea what actually happened- a major empire collapsed and its outlying provinces fell into anarchy and barbarian invasion, but there are hints something darker and more terrifying might actually have occurred. Non-human races do exist- dwarves are sometimes allies of humanity, but mostly stay locked in their holds, and seem fearful and tight-lipped about the past. Elves are faerie creatures, and are not available as PCs- they are the failed attempt by the fey to create human-like creatures, but they don't possess souls, and are resentful and cruel to humans. Halflings exist, and they are mostly like hobbits- small cousins of humanity that cling to humanity for protection, but they are also mechanically adept (clockwork tech mostly). Orcs and goblinoids exist- mostly they are barbaric raiders, but some legends exist that tie them to lost tribes of humanity in the far north that were changed somehow. Magic can be dangerous to the caster- sometimes resulting in the subtle changing of the caster's personality and more rarely his body as his learning progresses. Many arcane casters fall into madness after particularly harrowing mystical experiences. I tend to run more investigative and suspense oriented adventures, with the occasional foray into S&S (exploring ruins and seeking clues about the past)- in feel its a lot like the movie The Name of the Rose. When I started this campaign right after high school, it was a big switch for all of us- we were used to typical D&D high fantasy, and wanted a change. After 15 years the game is still going strong, and as our tastes of changed, we've developed the world and its mysteries and found a big thrill in just exploring the world (and even as the DM, things still surprise me when we game- I'll have an on-the-spot inspiration that really works out being cool).