I love the San Luis Valley of Colorado and the ride to The Great Sand Dunes National Park from Blanca is below Mt Blanca and as you approach the Park you begin to see the Dunes off in the distance.
I did not stay at the Pinon Flats campground but I did check it out and the views are stupendous.
The visitor center has a film and exhibits and a great deck.
You can walk among the dunes and at certain times of the year there is water from Medano Creek to wade in.
Definitely worth it if you are anywhere near.