I think it's okay to sit for some acts (not most) but it's hard to judge.
Example: I saw REO Speedwagon/Styx/.38 Special in June. Everyone sat for .38, stood for Styx, and about half and half for REO.
And when I saw Alice Cooper at the KS State Fair, everyone stood (to my surprise).
09/18 - Clutch
09/19 - BMTH
09/20 - Fuzz and Fire 2
09/22 - RA/TA/Radkey ?
09/23 - Crowbar