Here is one of the best DEALS around...buy a National Parks and Federal Recreational Lands Pass-Senior Pass and become the most popular guy on the block. Really!!! You can take passengers in your car into any United States National Park and never pay a penny again. Not bad for an initial $10 fee.
We have visited National Parks all over our country using this pass. Really the saving have been enormous. We have taken friends with us over and over into places like Zion National Park and Saguaro National Park. They are always amazed that we just drive up, show our pass and go into the park. Everyone else is paying at least $25 per vehicle. If you are a senior citizen, you really should take advantage of this advantage! (National Geographic Guide to the National Parks of the United States, 6th Edition)
We also have a US National Park Passport book and have added stamps for all those park we have visited. I wished we had done this when we were much younger. I think they would make a nice gift for a young family. The cost is $8.95 at eParks.com.
I just thought you would want to know.
PS Thank you Marcia for reminding me of this. I had totally forgotten to tell anyone about it.