What are your favorite spots?

I'm trying to plan an itinerary for a hiking/nature/exploration trip in the Pacific Northwest but we're so flexible that it's pretty hard to do, I could really, really use some help from you lovely people!

I want to hike and see the gorgeous nature views, maybe swim near a waterfall or find some hot springs if possible (I'm not sure about the nude springs though). We don't have a car, but I'm hoping we can find buses/public transport to take us from place to place

I'm contemplating hopping from Eugene to Portland and maybe Seattle, but I'm not married to any decisions yet. I think the best way to plan the trip is to start with finding the absolute most important places to see and plan around that. As someone who's never been to the area at all, it's hard to be able to discriminate between all the different parks and forests and such.

If you could be so kind as to share any ideas you might have, like the most beautiful forests in your opinion, secret hot spring spots, or your favorite hiking trails, or even an argument for or against visiting certain cities and what to do there, I'd be very grateful.