I'm planning on getting some fall foliage shots on an upcoming trip to California (and in Upstate NY), we'll be hitting up pacific highway 1, yosemite national park, san fran and the mojave desert and a polarizer is a great filter when used properly. I'll be also using it to cut down glare on water and get more saturation with certain shots.
If you're looking for one, just remember for a digital DSLR you want a Circular Polarizer.
I'm so pleased with my Variable ND Heliopan filter I chose them again.
I haven't even got to shoot with it yet so I will update this if something noteworthy happens.
Heliopan website: http://www.heliopan.de/produkte/polarisationsfilter/
B&H Link: http://www.bhphotovideo.com/c/product/232513-REG/Heliopan_708246_82mm_Circular_Polarizer_Multi_Coated.html