Washington, bordering on Canada and the Pacific Ocean, is very scenic. The Cascades run from north to south, and are covered by the long and strenuous Pacific Crest Trail.
This wilderness counts a string of national forests and parks, with many thousands of miles of trails. Best are Wenatchee National Forest, Mount Baker-Snoqualmie National Forest. Okanogan National Forest, Gifford Pinchot National Forest, Mount Rainier National Park with its 93 mile circular Wonderland Trail, North Cascades National Park and Colville National Forest.
A different and very scenic part of Washington is the Olympic Peninsula, with its National Park and National Forest.
Finally, we should mention the American Discovery Trail and Pacific Northwest Trail.