A favorite place for nature lovers to visit is also the Japanese Gardens and the Lan Su Chinese Garden, both in Portland. The architecture is blended into the landscape of both so it is very immersive.
I vaguely remember visiting the redwood forests and museum when I was very young. Lots of historical logging stuff. The feeling was not so much, "look how tall the trees are," but rather being surrounded by a wall of trees you can't see over the top. Ever been in a room with walls so high it feels like they go up forever?