I am fairly familiar with Eastern Washington. I go to Wenatchee multiple times a year, and my Brother in laws Brother is a Fish and game warden.
Every year when I go over to visit with the In laws I go out on an ATV with a spotting scope with reticle to help count and try to measure Elk Bulls, Mulie Bucks and more importantly the mountain goats and bighorn sheep in Chelan county.
And My strategy that has worked well for the last 5 years is to look for the White mountain goats on the steep cliffs and hills, because usually there will be some Mule deer or the occasional small Elk herd in the lower elevations.
I dont know if the Deer and Elk Follow the sheep and goats or if its the other way around but where there is one there is usually the other.
Anywhere in Eastern Washington there is a serious potential for long range, even in the more hilly and cliff ridden eastern part of the cascades there are alot of really long sightlines.
The Hanford herd is in mid to lower Grant County, the middle of Grant is very flat and full of farms, there is a large ridge with about 2600ft elevation that cutts the Hanford monument area off from the rest of the county and I suspect most of the elk will be on both sides of that mini range and in the forest in the southern part of the county.
The south is more forested with alot of evergreen trees, But if you set up somewhere on the side of that Ridge overlooking the Hanford monument/forest you will have all the range you could want its 5 miles from the top to SR 24 . But wind will be a bitch.
Western Franklin County is more "flat" with alot of smaller elevation hills, and a little bit more of a dense forest, so depending on your hunting zone you draw you may be in a more wooded area where you should still be able to find 500yd+ targets but over 1,000 may be unlikely.
Hope that helps, I am not a big hunter, my experience is just finding them, I do like to go on foot once I locate them and get as close as possible to take some pictures, but thats all the shooting of Elk deer and goats I normally do. I do shoot tons of pesky groundhogs that love to burrow in softer orchard land, but thats another story.