Luggage and bags:
Clothing/Shoes/Weather Gear: Walking/Hiking shoes, whether you are touring main street or taking advantage of the many excellent trails in the area (the Colorado trail runs from Durango to Denver), chances are you will be spending a lot of time on your feet.
Light, comfortable clothing in the summer, warm layers in winter (depending on the day I wear anything from a t-shirt to a winter coat)
Many people would want to bring a hat, the sun is much more intense in dry climate at 6500 feet than it is at sea level.
Mid-July through mid-September is our monsoon season, accompanied by sudden, brief downpours and thunderstorms in the afternoon.
Toiletries and Medical Supplies: Sunscreen!
If camping, don't use fruity shampoo if you can help it, the bears are really hungry this year!
Photo Equipment: Anything you want!
Camping/Beach/Outdoor Gear: If you decide to go camping or hiking in the mountains or the desert, be sure to bring plenty of water! Every person in your group should have their own supply when hiking, preferably more than those dinky little 8-12 oz bottles. The dry climate, wind, intense sun, altitude, and physical exertion all conspire to dehydrate you. A properly hydrated person will have more energy and will be less susceptable to altitude sickness. Remember, if you start to feel thirsty, your already 2 quarts behind!
Also, if you are camping, make sure you keep your food in a bear-resistant location and never sleep with food or wrappers in your tent! Nylon will not stop a bear!