Yellowstone
If you have not visited Yellowstone it should be on the top of your list. It offers a lot of everything. From the amazing landscapes and thermal features to the animals roaming the park. I have been there in June and September. June is amazing as everything is green but most of all is the BABIES. You can not go wrong with baby bears and the baby bison (red dogs). But even in June be ready for all sorts of weather being at 8,000 feet. We had a dusting of snow one night. September Animals are fattening up for the winter as everything is changing colors. Fall is also a better time to see the wolves in the Lamar Valley early in the morning or late at night. If you stay in the park you have to stay in the original Old Faithfull Inn. With the communal bathrooms and all the old wood timbers. The best is relaxing in the lobby at night and listening to the music and relaxing after a long day in the park.