On the topic of Yellowstone, I highly recommend an app called GyPSy. The $10 you spend on the Yellowstone tour will be the best $10 you have ever spent on an app! It connects to the Bluetooth in your car and gives you an audio tour through your phone's GPS (bring your charger!). My kids (now 7 and 13) have learned a ton about the park, its geological features, wildlife, history, and it helped us from blindly driving around the park.