Water, Grand Canyon National Park
Miscellaneous: No one should try to hike into the Crand Canyon without carrying sufficient water supplies. During the summer months it will get very hot below the rim of the canyon to the point that the extreme heat can become life threatening without preparation. Bring at least a gallon per person to be on the safe side.
Luggage and bags:
Only what you need. Remember to bring at least one gallon of water per day, sunscreen, sunglasses and a visor to protect against the sun and heat. An extra pair of hiking socks is also a must.
Clothing/Shoes/Weather Gear: Well broken in hiking boots and not sneakers. Also, bring raingear. There are monsoons in the summer and the winter months can bring storms as well. Also, DO NOT WEAR OR BRING JEANS. Denim does not dry quickly if it gets wet. It will only weigh you down.
Toiletries and Medical Supplies: Again, only what you need. A first aid kit with aspirin, ibuprophen and band aids for blisters are a must.
Photo Equipment: Definitely
Camping/Beach/Outdoor Gear: Trekking poles are a good idea
Miscellaneous: Remember to pack out your trash!