I recently saw the documentary "Monumental: David Brower's Fight for Wild America" and I really liked it. It has some excellent vintage video of the Sierra and several parks. It has some video of Tioga Road as it's being built. I found the section on Glen Canyon to be particularly moving.
If you are a Netflix user:
http://www.netflix.com/Movie/70038140?trkid=73
If you are a GreenCine user:
http://www.greencine.com/webCatalog?id=130731