I keep it waaay coarse. My best V60
brews were closer to a french press grind. 20g for 10 oz. of cup. (I think your 12 oz is too much). I'm gonna perhaps get a little controversial here, but I believe that the goal when brewing filter/drip coffees of any kind is to extend the brew time as long as you can... as close to 3 mins 30 secs or so as you can. More and more, I'm finding myself convinced that you simply can't brew a truly great cup in 2 or 2.5 mins, or shorter. You can't cheat chemistry. With the V60
's, I found that by using the long-neck pouring pitcher, you could keep the bed low enough to maximize the flow-restrictiveness (so to speak) of the grinds. If you floated the grinds or tumbled them too much, the water would flow too quickly out the bottom, and you'll have a weaker brew that ends too quickly.
I was all ready to launch a brew bar with the V60
's. After much experimentation and deliberation, we're opening Chinatown Coffee next week with a manual brew bar using Abid/Clever drippers. It's much less finicky than the other manual brewing tools, and it's very easy to train someone to create a totally badass cup. Our barista staff is flipping out about how dreamy the coffees have been off the Abid/Clever drippers.
Sorry... don't wanna thread-jack, but just thought I'd share. Somewhere, out there, Scott Rao is smiling and he doesn't know why.