Well Mark, we've run for a long time in a flavor (if that is the right word) intensive game.
It's set in our real world in Constantinople with plenty of realism. We use real world weapons, political organizations, institutions, governments, rulers, historical figures, war-situations and enemies, religions, etc. The players love that they tell me. (And I love it cause it makes writing interesting adventures and missions, as well as campaign plots, really easy to construct. Though complicated to construct.)
So "realism" and historical involvement are big factors in the game. It adds to how well and how deeply the characters can become immersed in and personally involved in the world, campaigns, and plots. My personal theory is that it is much easier for players to personally "associate" and be sympathetic with cultures and groups and peoples and nations and religions they know and have something in common with. I also let my players use their own real-world skills in game. For instance if they are good at survival skills, or know how to track, they can use those skills in game, as if they and the character are the same person. This also adds to what I call Player-Character Sympathy. In some ways the characters are characters and in some ways the characters are the players. So real world issues (current affairs are written into adventure and campaign plots, just in historical form), realism, player-character overlap, etc. are all fundamental to the milieu.
That being said there is also another world, like ours, filled with non-humans, Elves, Dwarves, Giants, etc. That world is filled with magic and staring things and overlaps our world. In that world very bizarre and "otherworldly" things can and do happen.
The "interplay" between our world and the other world is what makes the setting able to do multiple things at once and allows humans and the human world, and non-humans and the non-human world, to operate very differently. One aspect of play I always enjoyed from the video-game Tomb Raider was the difference between things working "normally" (and yet still dangerously) in the regular world, and yet once she penetrated into the "underworld" of the bizarre, things operated completely differently. So I've tried to replicate that in my D&D milieu, and in the other games I've invented or written.
There are two competing aspects occurring at once, normal life, filled with national, tribal, and ethnic enemies, thieves and criminals, dangerous and cunning people, political forces, intrigue, tyrants, human monsters and human evil and good, etc. - and then there is the other world filled with monsters, angels, demons, dangerous magic, strange creatures, and so forth, and it is concerned with supernatural, preternatural, and unnatural and non-human evil and good.
I like the overlap and the conflict between these two different types of "flavor." You might call it.
But it makes demands that I greatly modify the "normal editions" of games. For instance our fantasy game is mostly D&D based, but some might consider it an entirely different game (and I am revising and writing it up in that way - I've been wanting to do that for years) though others might call it just an extremely complex and highly house-ruled D&D milieu. I guess it would depend on your point of view.
I'm not sure I answered your question in exactly the way you're shooting for.
But that's my stab at it.
I like "flavor" and find flavorless games boring, and I like role-play and find killing things just for the sake of killing things boring as well. Especially over time. (Though killing really evil, clever, cunning, crafty, and powerful things can be an awfully exciting tactical challenge, it is not what role play is ultimately about to me.)
