ive seen opeth too many times to just stand there in "awe", moshing is fun especially on some songs like deliverance, demon of the fall or white cluster.
Gorgasm, Impaled, Novembre, Vital Remains, Zyklon, Aborted, Carcass, Behemoth, Agalloch... Just some bands with interesting lyrics instead of the usual 'fuck' bands.
Here's the meaning behind Ghost Reveries http://www.funeralportrait.com/song-meanings/ghost-reveries.html
Of other albums http://funeralportrait.com/song-meanings.html