Hi Mike,
I have a circular polarizing filter on my camera for probably 90% of the photos I take but my camera automatically adjusts the stops (+1 in my case). The polarizing filter helps bring out the blues in the sky, making then darker and clouds whiter, adds contrast to B&W pictures (which I mainly take) and reduces shine when taking images of cars, buildings (windows) and brings out greens in landscapes and helps reduce haze in photos etc. Its a very useful filter to have.
I then have a clear UV over that to protect it as it was not cheap!