If you haven't had the opportunity to drive GTTS you should certainly plan a trip to Glacier Nat Park so that you can do that. Glacier is where the Gods sat when they created the rest of the world, and this road takes you right thru the middle. 2-lane, narrow, very windy, no vehicles/RV's over 21 feet, average speed 20-25 miles/hour. Scenic viewpoints every 50 feet or so, and if you sneeze at the wrong time you may find yourself trying to 'drive' vertically down the face of a cliff. If you want to see some pictures of what GNP is all about, go to glacierparkchat.com and look around.
P.S.....if you don't like mountains, forget it.