Some prepackaged first aid kits are better than others. Here are some near-perfect prepackaged kits that are available:
The Walkabout First Aid Kit from Atwater and Carey. In addition to the usual first aid accouterments, you'll also find pill vials, sting-relief pads, antibiotics, and antihistamines (Benadryl). The nylon case has plenty of room for extras you might want to take along.
Johnson & Johnson's First Aid Kit. This plastic, lightweight kit holds every type of bandage and gauze you'll ever need. And there's room to add your own individual supplies.
Johnson & Johnson's Compact First Aid Kit. When room is a luxury, consider the compact version. It has almost everything that the larger size has, but fewer of each item.
Healer Products First Aid Kits. These lightweight, plastic kits contain just about everything you'll need in any emergency, including a superb antiseptic burn spray and an instant ice pack. These kits also come in various sizes.
And you might want to consider adding these items to the basics in any kit:
The “Snoozle.” An inflatable pillow you can use anytime, anywhere, from airplanes to tents. They are especially useful if someone gets sick with the flu or a fever and needs to lie down comfortably.
Skeeter Beeters from TravelSmith. These nylon mesh pullover pants, tops, and hoods have elastic at the opening to make a perfect mosquito netting without the bed!
An emergency thermal blanket. REI makes one such blanket, which is a thin sheet of insulating material similar to those created for the Apollo space mission. It folds easily, and it actually works to keep you warm. It's especially good for hypothermia emergencies.