I just came back from a short trip, driving the I-70 (actually, the CO-93, I-70 and I-15) between Boulder, Colorado and St. George, UT. Some of the most spectacular scenery I have ever seen: mountains, rock formations, and vistas. I do not know how accessible any of it is, but it would be worth weeks and weeks of photographing to scratch the surface. I am not a landscape photographer by any means, but this was awfully tempting. Sadly, I didn't have the time to stop but it sure made me want to go back.