Luggage and bags:
Daypack is definitely needed, as you might want to do some hiking tours.
Clothing/Shoes/Weather Gear: Whenever you will visit Arches NP, be prepared for all kind of weather. In summer, it's surely hot, but it might get cool in the evenings. If you are still on a hike by then, you might like to put on your sweater. If you go in winter, bring windproof gear with you, mainly if you do the hike to Delicate Arch. Raincoat might also be handy, in case of summer thunderstorms.
Toiletries and Medical Supplies: Sunscreen is a must in winter and summer, a hat to protect from the burning sun comes handy.
Photo Equipment: Bring enough film material, rolls or batteries, a second chip for digitals (or a storage device) might be useful, as the scenery just calls for pictures !
Camping/Beach/Outdoor Gear: If you want to do some backcountry hikes, all outdoor gear is needed, including cooking equipment.
Miscellaneous: Water - water - water - water.. be prepared and bring minimum 4 l per person per day.
Hiking poles are not neccesary, but also might come handy, if you are not used to trails like these.
Luggage and bags:
Arches is not a backpacking park so a day bag will suffice for their relatively short hikes.
Clothing/Shoes/Weather Gear: Sturdy hiking boots are needed for the sometimes tricky terrain and slick rock you will be walking on. Long light pants and shirts help protect from the often brutal sun and also keep you warm in the cooler early morning hours. Hikes are short so no need to carry extra clothing, just get back to your car.
Toiletries and Medical Supplies: Sun screen is truly essential in SUNNY Arches.
Photo Equipment: A polarizer will help cut out the sun's bleaching rays but the best course of action is to shoot when the sun is low, early morning, late afternoon. Tripod for cute couple photos.
Camping/Beach/Outdoor Gear: This is one park you will truly want to camp and nothing beats tent camping when the spots are as big as they come at Arches. You can set yourself up on a sandy patch right in the red rocks you've come so far to see. A warm sleeping bag and mats are a must. As hot as it is during the day, it still gets chilly at night in the desert.
A good sun hat is important any time of the year.
Photo Equipment: Be prepared to carry your camera equipment; so do not pack along anything you are not willing to carry while hiking. A zoom telephoto lens such as a 28-200 or 28-300 is good to carry. If you do not wish to carry a tripod, a hiking stick with unipod capabilities will add some extra stability for that shot.
Camping/Beach/Outdoor Gear: Sturdy hiking boots and a good telescoping hiking stick are invaluable if you are planning hikes into the more difficult terrain. Even for short easy hikes, comfortable walking shoes are mandatory at all times. If you are backpacking into the backcountry, you must carry your own stove and all the water you will need.
Sturdy shoes are a must. Park warnings also caution against sudden high water and flash floods, so be attentive.
Toiletries and Medical Supplies: Sunscreen will help on most days.
Photo Equipment: A polarizer on your lens and perhaps a shade for the lens as well.
Miscellaneous: Bring plenty of water. Dehydration will be a factor no matter how much you drink.
Luggage and bags:
Backpack: both hands MUST be free for scrambling on longer or more strenuous hikes
Clothing/Shoes/Weather Gear: Shorts, pants
T-shirts both long and short-sleeved: heavy,100% cotton is the enemy in wet weather so quick-drying blends are best
Socks: a synthetic mix is best to avoid blisters
Hiking shoes or boots with a good tread: the stickier the sole, the better. No open-toe sandals
Toiletries and Medical Supplies: First-aid kit with sunscreen, pain-relievers (Advil, etc.) bandaids, moleskin, antibiotic salve, wet wipes, gauze, ace bandage for splinting, sterile tape, whistle or small reflector
Photo Equipment: Whatever you use - pack an extra, charged battery, Blowing sand/dirt can be a problem so lens cleaner is a good idea
Miscellaneous: Flashlight, binoculars, 2 water bottles, snacks (nutrition bars, gorp, etc.)
Toiletries and Medical Supplies: Edward Abby's "Desert Solitaire" is required reading for anyone visiting the Arches. It is essentially a collection of essays and recollections from his times as a Park Ranger in the 50's. In addition to Arches NP, he also talks about the history and geology of the region, his visits to Canyonlands, Glen Canyon and other places, and about the need for wilderness spaces. This book is considered a classic American work, and Abbey's use of prose is at times hilarious, angry, and powerfully evocative. Few people can put the wilderness into words like Abbey.
Good hikingboots are recommended as the trail goes over rough terrain (sand and rocks).
Photo Equipment: Again, enough films as one great shot appears after another.
Miscellaneous: Some foot and enough water is wise to take along on the trail.
The weather at Arches can be very harsh, because of its hot and dry climate in the summer. In the summer (from June through September) ,the temperatures go over the 100 degrees Fahrenheit / 38 Celcius. So if you plan to visit the park, bring plenty of water and protect yourself from the sun.
In the winter (December through February) it can get surprisingly cold. Temperatures below 32 Fahrenheit / 0 Celcius are not unusual.
Good hiking shoes with good tread and ankle support.
Photo Equipment: Zoom lens for out of reach places or wildlfe!!
Camping/Beach/Outdoor Gear: Sunblock!! On some hikes, there is no shade.
Miscellaneous: Carry more water than you think you'll need.