As has been said in various guidebooks and even on a few websites, the stories of mishaps, and hardships stand on Castle Peak. It is a striking peak that dominates the White Clouds. The White Clouds are a proposed wilderness area that sits across from the Sawtooth's, and in between Ketchum & Stanley.
There are over 25 lakes that are visable from the summit along with the Sawtooth's, Smokies, and even the Lost River Range.
Tom Lopez author of Idaho A Climbing Guide describes "Castle Peaks talus routes are in a class by themselves. They mix steepness with cliffs, talus with boulders, and present multiple route-finding difficulties"
I would say the standard route is Chamberlain Basin due to the realtive easy access, a class 3 scramble that involves plenty of route choices.
Take Highway 75 36 miles past Ketchum over Galena summit. Take a right on the Pole Valey Road
2.4 Miles East Take Germania Creek Road
Follow this road for 6.8 Miles to the Pole Creek Summit
From here access FST-047 which will lead you to Chamberlain Basin.
You will need to purchase a Sawtooth Recreation Area permit. It will cost $15 for an annual pass, or $5 for a 3-day pass.
Usual climbing season is from June to September. Can be climbed year round, but Avalanches and access are a major concern
Camping is allowed throughout the area. Best place to camp is in the Chamberlain Basin below the peak. Other parties will camp at Washington Lake, makes for a longer approach but it is a great place to camp also
Sawtooth National Recreation Area 800-260-5970 can give general info but not climbing specific.
The Stanley Ranger Station is a better resource but they are tougher to get a hold of.