There's a good one May 16 and 17 in Grangeville, ID that draws a bunch of shooters, maybe 300. May 30 and 31 in Lagrande, OR will be a great shoot, 150 or so shooters. June 20 and 21 in Missoula is a huge one.
The problem with getting into 3D shoots is the travel every weekend; it's also the fun part of the shoots-- seeing a new area.