CloudDriver wrote:
I'll just suggest that you head for Yellowstone. There are many good reasons why this place became the first national park in the world. Just 40 miles south of Yellowstone is Grand Teton National Park, with some of the most spectacular mountain scenery in the west. You can hit the South Dakota Badlands on the way. If you feel like heading further west and have any time left, go for it!
You haven't mentioned school age children in any of your posts. If you don't have kids in school and can get off from work in the Spring or Fall, you can avoid the high demand summer travel season. Many empty nest folks travel the shoulder seasons because it is easier to get camp sites without advance reservations and the popular destinations are less crowded. Our favorite timing for Yellowstone and Grand Teton is the first two weeks of June. We much prefer to see mountains with lots of snow still on them. We travel without advance reservations so we can stay flexible in our travels and have never had a problem. For Yellowstone, we have reserved a few days to a week ahead on a few occasions.
These are some good recommendations. Be aware that May & early June in WY, SD (Mount Rushmore) can be damp. We enjoy that time of year because it is off season. Doing the I90 tour is a good start to break in on longer journeys. You should be able to keep the long days down to 3-4 going out and 3-4 going back. Beautiful country through there and down through Yellowstone & Grand Tetons.