Not sure with way you are going to enter, so below is from the Twin Falls Idaho area.
If you take 75 up through Ketchum to Stanley then west on 21 to Lowman then turn right through Garden Valley to Banks then right , North on 55 through New Meadow and 95 north to 12 or at Stanley stay on 75 to 93 through Salmon.
At Idaho Montana line Take right on 43 to the Big Hole Battle ground. I've ridden all through this area you can't go wrong on any of it
I have friends who live in Hailey (north of Twin Falls) so we visited there on our way down to Phoenix and then back last April. I would suggest that you check out Craters of the Moon National Monument off highway 20 east a ways from Twin Falls. (Recent lava flows in wild formations.... recent in relation to earth's age.)
If you go that way.... you would end up on 93 and go through Lolo, Montana. From there, you turn left and you ride through Lolo Pass, which is a couple of hundred miles of mountain riding along streams and big sweepers.... after a couple of hundred miles of curves and sweepers to get there! Highway 12, Lolo Pass would bring you to Lewisston, Clarkston.... and south of there is 129 which is Rattlesnake Pass.... which is on the top 15 of the best motorcycle roads in the USA, according to the AMA.
Out west here, no matter which way you go, you will find raw nature and open roads. Be sure when you go home, you take a different path, but even if you do take the same path back, you will see different things.
Do not forget to look at southern Utah on your way.... and make sure you leave enough time to Ahhhhhhh.... on the way through.
No trip out west is complete without stopping by the Grand Canyon...... but that just all depends on how much time a person has.
Once you are back home, you will start to plan your next venture to the west. There is quite a bit of country to explore out here. I have been west now for 25 years and due to work and other commitments, I haven't been to as much as I would like. And some is worth doing over again.
No matter what side of the country you are on, you will want to ride to the other side. I want to visit the Civil War Battlefields on the east coast. Can't this year, but next..... I will be there, God willing.
Thanks that gives me great info and you are right about the will be back thing, this will be my 5th trip that way and Im just getting started. When you do come this way maybe we can do a get togather with some of us in the area. Civil War Battlefields are all around and so are great roads.