One good place to help with your trip planning is AAA. If you have a membership, you can go in and get maps, guide books and Trip Ticks. Even though we use a lot of online resources and Apps like Roadtrippers to plan our trips, we like having paper maps in the car/truck. Sometimes a GPS will be wrong in more remote areas or you will have no signal. Today, we went into our local AAA and got some maps and guide books for our California road trip in June. They even had some Yosemite and Sequoia/Kings Canyon Ranger booklets. These have some good info on visitors centers, hours, etc. I also grabbed some Alaska cruise brochures for future planning!
I will do a post soon on trip planning for a National Park trip like Yellowstone or Yosemite. Planning can be overwhelming because a park like Yellowstone is so large. There are several lodges to choose from and you need to book a year in advance to get your summer dates!