GETTYSBURG!!!  My aunt and grandmother took me there twice when I was little.  That was when my interest in the Civil War began.  A few decades later, I got my wife interested in the Civil War.  While watching the movie Gettysburg, I looked at my wife and said "I just realized I never took you to Gettysburg."  I took her and our daughter on a whirlwind, one day trip to guage her interest, with a promise that if she liked it, I would take her back.  My wife loved it.  Due to her excitement, we forgot to eat lunch.  Luckily, she went through 8 rolls of film and needed more.  That was the only reason we were allowed to leave the battlefield.  We went back at least four times.  Our daughter enjoys the ghost tours.  We even took the tour guides advice and went on the battlefield at night.  It was the best time we had.  Yes, some picture do have some questionable images.  We love the monuments.  My wife loves the dog.  We have fantastic vacation memories of Gettysburg.
A few years ago, my wife and I went back to see the new visitor's center.  They did a great job with it.  We also walked to the Seminary.  The Seminary is so peaceful, yet as we walk along the quiet street, we know the fighting that happened in the nearby fields.
I also dragged my wife and daughter to Harpers Ferry, because my aunt and grandmother took me there during our Gettysburg trips.  I told them they will probably be bored because it is just a small town, but we are going because I was there when I was little.  They loved it.  They don't know why they love Harpers Ferry, but they cannot get enough of it.

For me, it would have to be Wright Brothers National Memorial and Cape Hatteras National Seashore. Back in December of 2003, I was asked by my employer, a cooperating association, to travel to Wright Brothers National Memorial to assist with a very important event that was being held there, the First Flight Centennial. Traveling 400 miles to a cold, windy sand dune right before the Christmas holiday was not my idea of a good time. But I agreed to help nonetheless, since I didn't really have any plans anyway.

Although it was five long days of back breaking, bone-chilling work, it turned out to be one of the most prolific experiences of my life. Not only did I meet people whom I would form lasting friendships with, I had an opportunity to meet two Tuskegee Airmen, who were making an appearance at the event. Although I only talked with them for a few minutes, I was overwhelmed by their humility and kindness, and the fact that I was in the presence of living legends.

After the event, I agreed to stay on and help with the clean up effort. The day before I left, I drove to the beach and sat on the sand. I was overwhelmed by a lingering feeling that this was where I belonged. I couldn't explain it, but I knew that I would return sooner or later.

Six months later, I accepted a transfer from my company, and moved to Kill Devil Hills, NC. I ended up staying three years, and can say that living and working in the Outer Banks parks was one of the most fulfilling experiences of my life. It instilled a love for nature and the parks into the very depths of my soul- something I will always be grateful for.

You want us to choose only one?  That's as bad as asking us to choose our favorite Thanksgiving day pie.

Another great NPS Historical Site: Celebrating Albert's 250thBirthday, Secretary of the Treasuryhttp://www.nps.gov/frhi/parknews/gallatin250.htm
When the USA had a great credit rating vs Debtor Nation todayThe Youthful USA Funded three wondrous Ideas:1. The National Road, first east-west American road prior to railroads2. Successful Lewis & Clark Expedition3. Expensive Louisiana Purchase.

[The referenced park is Friendship Hill National Historic Site, which honors Albert Gallatin, 
Secretary of the Treasury during the Jefferson and Madison administrations. Among his other accomplishments, Gallitin is credited with reducing the national debt, handling the Louisiana Territory purchase, funding the Lewis & Clark exploration, and implimenting the National Road project. Ed.]

Come back, Albert, we and our country needs you!!!  With just this bit of knowledge I nominate Friendship Hill and Gallatin which blesses (could) the whole Park System if they would resurect his leadership and culture.

I did like Friendship Hill, but for the total experience of the visit, I would have to nominate Fort Bowie NHS in SE Arizona as my favorite.  I'd probably just like it for its general isolation to begin with, but it's so novel that the visitor needs to walk over a mile and a quarter to get to the fort that makes it extremely rewarding when you get there, and the overall setting of the site completes the experience. 

Gotta go with California sites (since I love California) Cabrillo National Monument - A small site with a lighthouse that's easy to explore.  Tidepools nearby and an easy day trip in San Diego

Manzanar - Perhaps one of the most important historical national parks in California, as it shows one of America's greatest mistakes - the incarceration of Japanese-Americans. In the windswept desert just not too much north of Lone Pine, CA.  Check out the graveyard for a white pillar monument against the backdrop of the crest of the Sierra Nevada.

C&O National Historical Park. Imagine a ribbon of history paralleling the Potomac River from the tidewater at Georgetown in Washington, DC, to Cumberland, Maryland, deep in the Appalachian Mountains. It's 184 miles of social, political and industrial history and geography from pre-Colonial times to the present. I doubt that there is another unit in the organization that contains such a range of historical and natural themes. Every Traveler reader should plan a visit to this fascinating resource, one that very nearly ended up under a parkway.