So, maybe you'll never be able to actually hike the Grand Canyon or to the Delicate Arch. But you may still be able to digitally.

Check out this video from Google about their Treks feature - which seems similar to the Streetview stuff but it's completely off the street.

(from a 2010 trip to the Grand Canyon)

(And, while we're on the subject, if I had to guess - I'd say the photo on that initial Treks page is from Arches National Park)