Wow! Why do you need a polarizer? These image are terrific! ( Didn't know how to contact you except through your blog....for my Seven Devils shot from Hurricane Creek Rd between Enterprise and Joseph, I had a kit 70-250 lens on my Canon T3i...and I "bumped" the saturation in Topaz Adjust.)
I've used a polarizer and it seems a little tricky to me. I guess I have more to learn in that area.I love the first shot - how the lines in the field draw your eye to the mountain. Beautiful!
I like a polarizer because it can darken skies without having to postprocess. It also will do away with or replace reflections in water or glass. It sometimes adds contrast to situations that need it! Just play around with it.