Yup. Getting this conversation started already. Learned the hard way for version 1.0 that many great group campsites fill up a year or more in advance so it's never too early to get the discussion going.
A few things…
I don't have to take the lead on this so if someone else has some fire in their belly to run with this, I'll happily hand over the reins and help out where I can.
I hoped for 30 people to show up but less than half that did for a number of reasons. I think finding a campsite that will accommodate 30 attendees is fine for 2016.
PNW GGG 2015 was a fun car camping event. Nice enough campsite but not nice enough to return to next year for a few reasons, including some road noise.
2015 was a car camping event, but we all agreed that we'd prefer a group campsite that requires some sort of hike in. I'm all for this except I don't know of a campsite in Washington or Oregon that requires a hike in that will accommodate 30 people.
Thoughts?

