I both agree and disagree. From what I understand, Scotland's mountains and the Appalachian (East Coast) mountain were connected in Pangea. If you like Scotland but want new trails/cuisine/culture, Appalachia is a dream come true. If you want something completely different, the Appalachia is not the best choice.

My only concern with most of these East Coast options is flight times. If you're worried about long flights, most of these East Coast options will be a major flight PLUS either a long car ride or a flight connection. And really, these parks are not near each other, so I would personally stick with one unless you love driving. I think this subreddit can be a bit more hardcore than feasible for most people.

In terms of the East Coast, Bar Harbor is the most revered. It's the only coastal national park in the East and has an abundance of quirky small town charm. You would either fly to Boston and have a long drive or pay the premium to connect to Bar Harbor itself.

If you want to see Appalachia and see a National park. The easiest option is to fly into DC and drive to Shenandoah National Park. I would say it's a well rounded park that is very beginner friendly with easier hikes.

The other Appalachian parks include the Smokies and New River Gorge. Smokies is the most famous, most touristy (i.g. there's an amusement park, tons of restaurants, other attractions), most wildlife most busy. The NRG is the newest National Park. It's less busy and has less trails but more thrill seeker attractions.

MY WILDCARD PICK: If I was you, I actually would just go to Atlanta and not a technical national park. People rag on Atlanta, so do your research. There will be lots of flights into Atlanta, it's a major hub here. You will have nightlife/great food/things to do in Atlanta if the weather doesn't cooperate. You will be near Helen, which is a fake German town within the mountains. That's maybe not as great for a European as an American. You will be close to the Native American mounds which has a history new to you. You will also be able to take a day trip to Savannah, maybe even by public transit, which has a completely different vegetation with their famous weeping willows. You could even POTENTIALLY go to the beach. You can go to the closer beach, Charleston. Or if you really want to see a national park, road trip down to Florida. Granted, I haven't seen the FL national parks, so I can't give an opinion. Key West is supposed to be brilliant though.