Does Canon recommends any filter? Why do you think you would need one? Get the lens hood, learn to be careful. It's foolish to believe that piece of metal / glass screwed on your lens will prevent serious accidents. A lens hood is the better choice. Everything that can be cleaned with a lens cloth and cleaning fluid does not need a filter.
Erm.. night scenes, cloudy sky and other moments outdoors will not benefit at all from a CPL. Use filters when needed, not just 'keep on everywhere'. CPL filters reduce the amount of light by about 2 stops (depending on brand, type..). In some situations this can make a difference.