I have been up there late season, S. Cle Elum Ridge, Peoh Point area.
Seen a lot of deer, Seen a good sized herd of Elk on the old "Circle K".
Have noticed that most Elk seem to cross the Creek into the Manastash, if you can be there BEFORE they cross,

Or take Cedar Creek to top of ridge and hunt behind private land (be aware of boundary)
Hope for Snow !!
The only time I have ever been in a "Migration" was in the L.Naches years ago, 100's of Elk coming down out of the Wilderness right before dark.
Groups of from 8-50 just streaming out of the trees !
What an awesome sight !
But it was a LOT of Snow right before we got there, as in a couple feet.