I am just going to echo everyone's comments here--if you do not go here, you are missing out on a LOT. This is especially true if you are from Northern side of United States, or like me, from Canada. The sights are truly something to behold.
One thing nobody has mentioned though, is neat the road is. I would love to come here first thing in the morning and drive really fast around the twisties hehehe. But of course, that would be illegal, as there are speed limits posted. =)
Tip: Go to the washrooms before entering... they have outhouses scattered throughout, but you probably don't want to use it!