Watch the ZZ Shuffle - Rhythm online guitar lesson by Jeff Scheetz from Rock Solid
For variations on something like this you want to think small - let the groove keep it all going and add little bits of things without being too distracting.
Remember this is a 12-bar progression so we don't want to take away from that. You can do countless turnarounds and try other patterns, but keep it in the pocket!
Rock is no different than most forms of music - more often than not, less is more.