Before I start getting into our trip, let me just say that we did not spend nearly enough time in any of the National Parks to see everything there was to see. But we did spend enough time in most of them to see the cool stuff and get a taste for what the park had to offer.
If you are looking for a relaxing trip and deeper insight into any of the National Parks, plan on spending at least two days in each of them and do your research on the parks prior to arriving. That is the minimum you would need to be able to see what there is in each of the parks.
As for us… we like it fast and furious so we spent one night in each of the National Parks, staying at the campgrounds in all of them* and having done our research on the drive to the park we had a plan on how to see all of the highlights that we wanted to see before having to get on the road to make the campground at the next park before loosing our reservation.
So this is going to be a taste of the National Parks, just enough to show you what you are missing by staying home!
*except the North Rim of the Grand Canyon which was full, we stayed at a campground outside of the park instead