What time will you be leaving Friday afternoon ? I personally would look at taking US93 to Twin Falls from Vegas and then I88/82/90 towards Seattle. If you are prepared to arrive Monday night you could look at taking in a couple of sights along the way otherwise your time will be filled with driving and resting.

Make sure you have a good paper map and do not rely solely on electronics, it's important to be in charge of where you want to go.