Within minutes of Oregon Hill and without crossing Pine Creek there are a bunch of small streams worth fishing. Check out any blue line on the PA Atlas and you'll find them.
Some places within minutes of Oregon hill will be cold all summer so there isn't a need to worry about where to fish near where you're staying
Of the 2 big runs, Slate and Cedar, I prefer Slate Run. There are more mid-sized tributaries on Slate, and if Slate is too warm, which is likely in August, you'll have options. I've fished both Runs extensively and also know the tribs, if you want a little more detail PM me.
Don't ignore Babb Creek, but go up above Landrus, it will most likely be a bit warm below that point in August. It's tribs will be cold though.
In August I'd not fish the lower ends of the larger creeks, they will be on the warm side. However if you do want the experience then go early, like sun-up and you'll be okay, just monitor the temperatures as you fish.
Water levels get pretty low in August, if there hasn't been rain in a few days so don't be surprised to find a lower end of some creeks dry. Some of them sink near the mouths.
My fly of choice for August up there is a stimulator in a # 12 in either green or yellow, a lightening bug, a bit late maybe, but trout will take them, and beetles and ants. I don't use ants on brookie streams, because I feel it actually harms the brookies, they usually inhale them and swaloow them deep. I don't like the idea of unnecessarily killing trout I don't intend to eat.
Streams that rise on Oregon Hill are Trout Run, Big Run, Dixie Run, and English run, all hold wild trout and some are more remote than others. I don't know much about streams on the other side of rt. 287, but many of those hold wild trout too. All of the trib to Babb Creek hold fish.
Stony Fork holds stockies all summer.
You may want to visit the Bark Cabin Natural Area (virgin hemlocks) or hike the Golden Eagle Trail, you'll find info on both on the DCNR web site.
Hope this helps.
I'll be at my camp during the weekend of Hickory Fest, August 16th, if you are going to be there at that time let me know.