Travelbooks

• Lonely Planet: "California & Nevada", ISBN 0-86442-644-5
  This guide gives excellent and mostly up-to-date information, rather more than you need.
• Lonely Planet: "Southwest" (Utah, Arizona, New Mexico), ISBN 1-86450-376-9
  This guide gives mostly great information, the desert area in southwestern Arizona could be of more detail.

• National Geographic Society: "Guide to the National Parks of the United States"
  This guide is excellent to prepare your trip while you're still at home. Whenever you enter a national park you get more actual information at the visitor center.

  

Nationalparks in the USA (Governmental homepage of the US national parks)