You will LOVE the Tetons - they are pretty magnificent - I can't give you any tips on campgrounds but if you are traveling in Southern Idaho it's pretty much Mormon country and sometimes some little restaurants no coffee, tea or soda.

but we're already trekking from California, we'll be doing tent camping and, well, we're not young people anymore. Montana is definitely on the "go see" list, though.

I just noticed I mispelled Tetons (Titons). Fixed it. My husband actually suggested the Tetons. I did some searching and now I'm really excited to be able to see it IRL. Btw, love the Yosemite picture -- I live about 45 miles from there.

my daughter lives in Hailey (Sun Valley) and tells me the hiking is awesome...

http://www.visitsunvalley.com/things-to-do/sports-recreation/camping

also Fun trip... Craters of the Moon!!

http://www.nps.gov/crmo/index.htm

Of course, if you're visiting from Riverside, it won't seem too bad...

We know hot.

(about 75 mi. north from Twin Falls), including Hailey, Ketchum, Sun Valley. Excellent hiking and you can take the ski lifts to the top of Baldy, if you want, and hike down.

Another 60 miles up the same highway will take you over Galena Summit and down into the Stanley Basin. Area includes several large lakes and many small ones. Redfish Lake is here--so named for the salmon which came to spawn--and the Main Fork of the Salmon River starts here. There is excellent camping at the lake, the Sawtooth Mountains are drop-dead gorgeous and the little town of Stanley has a number of rafting companies that can do day-trips (or they did last time I checked! I think the area had a good water year). Also a couple of fun bars and at least one decent restaurant.

It's about 30 miles southeast of Pocatello. You can get to Teton park on a less traveled path (all paved) from there. Since you will be close to Yellowstone Park you might as well do a day trip through the park -- you won't be disappointed.

http://www.lavahotsprings.com/

Have fun!!

Challis is my favorite town in Idaho, family connections.
The Challis Hot Springs Resort is a decent bed and breakfast and a great campground. It has a big! hot springs pool and is on the Salmon River. Beautiful country. A lot of mining history in the area, e.g. The Yankee Fork has a nearly intact mining town. You can even pan for gold.
If you swing northeast from Boise, you go through the Sawtooth Mountains, hit Challis, then turn southeast and head across the state to Arco, Pocatello and on into Wyoming for the Tetons.
Have fun and good luck,
Crow

there is also some hot springs. I don't remember the town but it's about the hot springs and there is an old hotel with the most beautiful hot pool. If you're interested, pm me and I'll get the info.