We are planning a trip from Northeast Georgia to Lake Tahoe (Heavenly Ski Resort) in December 2008. I've never done the cross country road trip thing before so we definitely would like to take in some "must see" sights on the way.

What is the best travel route for December weather while still being able to take in some "off the beaten path" sights? I know I want to see the Grand Canyon, but what are the other don't miss sights and how many days should I consider for first half of trip from GA to CA/NV?

Thanks!