Who signs 6-year deals? Are these common? I don't think either side wants that with depreciating costs on contracts. Maybe I'm wrong. That just doesn't sound right as usually 4-year deals are the norm. In any case, there are not many starting guards out there and Levitre's cost will be inflated which is why as a GM, I would lean towards the sure thing and try to extend Slauson. He knows the man-blocking schemes which took the OLine 3/4 of the season to effectively run. The continuity alone with DBrick and Nick counts as some value too.
I think in general, most of you have too big of a revolving door which will lead to more cost and less likelihood of quality players being available. The whole league will be targeting a lot of the same guys you list meaning you're not going to get them all. I think more will be kept than what I'm seeing.