Clothing
Choose clothing that is appropriate for the environment and current season of your destination. If rain or inclement weather is a possibility, then pack accordingly. Always include one extra set of clothes.
Food and Equipment
Planning, preparing and packing a selection of meals and snacks in advance is a great way to save money. It also frees travelers from planning their day around the need to find and purchase food in the area.
Campers, hikers and outdoor sports enthusiasts should include all of the usual equipment (tents, maps, cooking equipment, and so on) that will allow them to be comfortable and self-sufficient in the outdoors. Always bring a box of trash bags to collect waste.
Toiletries and First Aid
Call ahead and do some research into your destination to find out what, if any, facilities will be available (toilets or showers, for example), then pack accordingly. Sunscreen, soap or hand sanitizer, a toothbrush, floss, insect repellent and a first-aid kit are essential.
Entertainment
Always provide something to entertain yourself and your family during down time. For long trips, it's best not to rely on electronic devices, such as MP3 or portable DVD players, that require an outlet to recharge. Books, board games (especially "travel size" versions) and art materials are good options. Keeping a travel journal is a fun and unique way to record the experience and create a keepsake from the trip.