To avoid the "Boarding Kennel Blimps," ask the kennel to weigh your dog every day to make sure the animal is neither gaining nor losing weight, and to adjust the amount of food accordingly.
Always provide the name, phone number, location, and after hours emergency contact numbers for your regular veterinarian to the kennel. Make sure you've provided your veterinarian with written permission for the kennel to seek treatment of your dog, and to what extent emergency treatment may be provided in the event you can not be contacted.
The American Boarding Kennels Association accredits kennels that have met 200 standards of operation and have agreed to a code of ethics. Order your copy of their publication How to Select a Boarding Kennel.