Nice exposure - curious as to why you went to ISO 800... maybe you had it set to Auto-ISO and your camera tried to compensate for the use of a CPL? It's not as if it really hurts the image, just more of an idle question.
I had gone to Muir Woods on my way out to Pt. Reyes , where this image was taken . Muir was pretty cloudy/foggy that AM , and I found I was getting some shutter speeds , at iso 400 , that were slower than I liked , so I upped the iso to 800 and never bothered to put it back down . One of the nice things about the 5d/5d2 , and I guess most of the current generation of DSLR's is their performance at iso's that are higher than we considered 'normal' with film .A lot of times , if I know I'll be shooting inside and outside , and not using an IS lens , I'll set the iso to 800 and forget it for the rest of the day.