Start along any of the treeless major canyons east-side. Go up into the nastiest slopes short of cliffs you can find. Bring lots of water. About the time you cough up a lung, you'll be in them.
Yakima canyon, Snake River, Columbia River breaks through Chelan and Douglas counties, portions of the Okanogan River drainage, Moses and Grand Coulees, and pretty much any extensive treeless steep rocky country will have chukars. The distribution map in the upland pamphlet shows the major areas. You can use GoHunt on the WDFW online mapping, to scout out public lands; on private it's usually not too hard to get permission, though the ranchers might laugh at you for wanting to hunt those @#$%^&.
A wise man once said, you hunt chukars once for fun, and the rest of your life for revenge.
