Another one of the truly magical locations in Washington State is Mount St-Helens. It is a massive volcanic mountain like the rest of the peaks in the state with the difference that is missing its snowey cap. After its eruption in 1983, the peak of the mountain was blown away and spread as ash all over the state, but that only, in my opinion makes this mountain more unique and even more beautiful. In the right season, the wildflowers cover the valleys surrounding it and making it a truly beautiful sight.
Although the State Park has a whole bunch of different hikes, we really enjoyed the Johnston Ridge for a photo shoot. The parking lot is really close to the trail head, paved road all the way, and you dont need to hike far to get a nice view point of the mountain with the valley below. Since you are on top of the valley looking down and due to the nature of the park finding foreground objects might be a little difficult as there is little trees or other objects available, so hike around and explore the path before settling for your final shoot location.
Equipment wise, bring wide angle lenses, tripod and any nd/gradual ND filters you got, the lighting can be interesting to say the least some times.