Head A broad brimmed hat should top your head. This is absolutely essential - it will keep the sunlight off your head and neck. Avoid baseball hats because they don't protect your ears or neck. Make sure the hat has a chin strap and use it - strong winds can snatch your hat and carry it out of reach in an instant. During the cool months, also pack a knit hat to provide welcome warmth in the cool evenings and mornings or near the rims.
Sunglasses provide eyes welcome protection from the sun year round.
Put vanity aside and wear your regular glasses when hiking in the Grand Canyon. The canyon is a very dusty place. The dust will quickly get under your lenses and irritate your eyes. It is always a good idea to leave an extra pair of glasses in your car. While climbing out the Red Canyon trail, I set my glasses down during a rest break.