I find my tastes changing over time - I used to want authentick flavours, it didn't matter of what, really, but I wanted my Japan to be "really Japanese" and my medieval Europe to be "really medieval." Nowadays I've slid some distance from that position toward Xena - I want gonzo mashup more and find authentick a bit of a bore. Where do you find yourself on that scale?
The answer is: it depends. Slightly more detailed: I'm somewhere in the middle. Slightly more detailed yet: I can find virtues at various points of the spectrum, although too much gonzo makes me want to run for the hills.
I used to be more serious about setting. I actually put this down to lack of face-to-face game time. I'm not sure if this observation holds for everybody, but I think obsession with setting design is a kind of warped outgrowth from the mind of DMs who don't get the chance to actually play much. It was certainly true for me: I wasn't doing any face-to-face gaming (just lacklustre PBEMing and PBPing, which is generally quite lacklustre) and yet I wanted to - and I still enjoyed thinking about campaign worlds, drawing maps, creating bestiaries and NPCs, imagining trade routes and where resources would be found, dreaming up languages, and so on.
This also caused me to spend a lot of time and energy pursuing "authenticity"; the more time you have to think, the more you do think. I often thought about how to create a "really Japanese" game, for instance, given my experience living in the country and my interest in its history, and my utter loathing and disdain for the way in which RPG geeks approach the subject (which is either "samurai and ninja, cool!" or "anime, cool!"; there is not enough space in my head for my eyes to roll sufficiently far back to communicate how much I despise both Western anime fandom and samurai-wankery).
Now I'm gaming quite a lot, and I'm also really busy, so my thinking time has been drastically reduced. This has both removed the urge to pursue authenticity, and also the opportunity. So while my setting design does not lean so far to the gonzo, it certainly doesn't involve chasing after the pipe dream of realism either. My main priorities are, simply, "What will I actually use?" and "What will be good for the game?"
But that said, too much gonzo doesn't really do it for me either. At a certain stage, it all feels like trying too hard to be irreverant. This leads us back to a post about humour that I wrote a few weeks ago. There's a strand of geekdom that repels me really quite strongly, and which others seem to find unaccountably attractive; it is the kind of straining towards "gonzo" that leads to inquisitors in Warhammer 40,000 with names like "Obiwan Sherlock Clousseau" and religions surrounding vast floating puddings or called "The Church of the Lucid Shirt Button". That kind of thing is so unfunny and uninteresting to me that I can't put it into words: it makes me want to bite my own fist for want of punching it through the face of anybody who would suggest otherwise. If that's what "gonzo mashup" means then no, thankyou, you may keep it, and also please fuck off and die.
If, on the other hand, "gonzo mashup" stretches to "this is a pseudo-oriental setting so I am going to borrow heavily from Japanese, Chinese, Thai, Mongolian and whatever other mythology because hey, life's too short and really, who cares?", then I am all for it.