I have bought the annual pass several years. Just depends on how many parks you plan to visit during the year and what their admission fees are. The last time I bought one I was bicycling to Yosemite ($10 for cyclists) in the spring and then my daughter and I were taking an extended car trip with visits to a couple dozen parks between California and her school in Wisconsin. Definitely worthwhile to have the Park Pass that year since the regular admission fees would have been a few hundred dollars. The pass is good for 12 months and the beginning date is punched when you visit your first park. I also used it at a variety of local locations that are run by the National Park Service and charge admission fees: Muir Woods, John Muir home, Pinnacles, SF Aquatic Park museum, Lassen.