Whats a good relaxing National Park in U.S. for a 5 day vacation?

I’m doing this presentation project for Outdoor Education(P.E. class), and I need an idyllic national park for my presentation. One were it’s just me and the nature itself. I’m looking for a walk in the nature kinda thing, no money blowout shit. It’s suppose to be a 5 day stay, so help me out here. Only live in U.S. for 2 years so I really don’t know much about the country geography wise. : )

Of the ones I’ve been to (which is quite a few), if I had to pick one to spend 5 days at and just soak up nature, I’d probably pick Grand Teton National Park. It was beautiful.

Cape Hatteras National Seashore and Mammoth Caves NP are awesome too, but much different types of places than the traditional “hiking in the woods” kind of place. – - – Mount Rainier was pretty, but we were there in Feb-March which is the cold, snowy off-season. I bet it’s even better in the summer.

I have not been to Cumberland Islands National Seashore, Acadia NP, or Gulf Islands National Seashore, but I bet those are beautiful too. And anything in Alaska would be awesome!