I just got back from a two day hiking expedition in Michigan's upper peninsula. There is a bunch of national forests and places to hike. Specifically, I went to Tahquamenon Falls. The waterfalls were very pretty and the water was surprisingly warm, but it felt really good. If you don't mind not having cell service, upper Michigan nature is nice. So many trees still untouched.
I've also been to Hoh rainforest in Washington State, US. The drive there is super pretty with very tall mountains with lots of pine trees and streams running through them. The forest is a pretty good hike, just watch out for bears, haha. Bonus...you get to drive through Forks to get there..ya know..from the movie twilight lol.
If you're comfortable with the cold I'd recommend touring Iceland as well.