Hey Sean, were there many towers like this at Castle Rock? Pretty awesome looking. Was the rock very solid or was it the usual central Idaho choss? Glad to see your getting out so often.
Caslte Creek is one of the strangest and out of place drainages I've visited. Castle Rock is surrounded by towers like this. Now, I'm not a rock climber (yet), but it seemed to me that the rock was fairly chossy but climbable. I say if you have the time, go for it, the approach is short, and if the rock isn't worth it its a fun scramble to the really twisted summit and its not far from Porphyry either.