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).
2/19 - 1349
2/26 - Nappy Dappy
3/8 - Title Fight
3/17 - New Found Glory
4/7 - Weedeater