Hi noslack, I have fished the Swan River many times and it can be quite good for Grayling especially later in the year when the water clears up. As for access, if you have the Backroads book, use it to explore the area west of Edith Lake. There are many accesses on the mutitiude of oil roads in that area and all produce Grayling. Watch out though, that clay can get pretty greasy when its wet, which seems to be most every day up in that country!
We fish it mostly with ultralights and small spoons or spinners but the grayling always seem pretty active and should take any sort of small flies, although I've not seen to much surface action so you may want to try some small nymphs or Black Gnats. Good luck!