Yeah I know Valve really disliked that there was a huge organized group that was using tickets to gate who could and couldn't go, even if those tickets were ultimately free. You're better off to just take a few friends and contact Valve directly
I've emailed Valve before trying to set up tours for other groups and they never responded. I've emailed them and so have a few others a few times at least over the past year with no response. I think your best bet of getting in contact with them is to call them.
Posts
Someone organized a group outing via the forums, but you can always just set up your own without needing special organization.
Prime: '10, '11, '12, '13, '14, '15
West: '16, '17
East: '14, '15, '16, '17
South: '15, '16, '17, '18
Prime: '10, '11, '12, '13, '14, '15
West: '16, '17
East: '14, '15, '16, '17
South: '15, '16, '17, '18