Greenwell farms has an unequaled reputation on the Big Island. It is a pretty big spread, yet still seems to be run rather smallish with a nod toward conservation, organics, and daily tours of their plantation and facilities. Really good stuff, I suggest you peruse their site here: http://www.greenwellfarms.com/
I bought some good Kona coffee from PelePlantation a couple of years ago -- see site below. Also my favorite, from visits to Hawaii, has long been BadAss Coffee (http://www.1konacoffee.com/), although part of the attraction may be in the name. I prefer the dark roasts.
Yeah. I know a great place. It's expensive though. A hundred dollars a can. The bean pickers make three hundred dollars an hour. Not, bad considering what I pay my therapist. And she doesn't even give me a lift.
Also, it's shade grown and the plantation owner plants ten trees for every coffee bean picked. 100% organic,too.