Mike,
the Patterson, May, and the Pahsimeroi valley is quite open, lots of sagebrush, etc., a big valley between big mountain ranges that get a lot of snow on them in the winter. Closer to Challis there is more timber, albeit in patches. Be prepared to be warm in September with cool nights. A lot of glassing is in order. There are a few ranches in the Pahsimeroi valley, and you could get lucky and find elk moving from the hills into the fields and do some ambushing. Past Challis up towards Salmon the terrain is steeper, rockier, rougher and tough hunting. Do a google earth to see how the terrain lies. Light colored clothing is good.
Nate.