Since its creation in 1916, the National Park Service has been charged with preserving and protecting the country's most magnificent spaces so that future generations will be able to enjoy them. Each year, millions of people trek to these lands, seeking adventure, romance, peace, solitude and beauty. With Ken Burns' documentary series 'The National Parks: America's Best Idea' airing on PBS, our staff members share memorable visits to six of our national parks. GRAND CANYON NATIONAL PARK The temperature at Phantom Ranch was 109 degrees -- just one more reason to stay at the North Rim. Not that we needed one. Reaching the rustic accommodations on the floor of the Grand Canyon required more advance planning and stamina than we put into our trip. And, as the weather forecasts reminded us, the North Rim is cool. Literally. Daytime highs in August topped out in the low 80s, and that was considered unseasonably warm. It's harder to reach the North Rim -- it's about 200 miles from Flagstaff, Ariz., a major reason the South Rim is far more crowded -- but the payoff comes on the trails, shaded by the spruce, Aspen and fir trees of the Kaibab Kaibob Forest and virtually empty once you've hiked more than a mile or so from any starting point. Every stop offers a photo-ready moment. But take time to watch for wildlife -- we saw white-tailed Kaibab squirrels, a breed found only at the North Rim, a California condor, mule deer and, once, a herd of bison grazing just inside the park gates. And just outside the park, we watched coyotes stalk the deer at dusk. Don't miss: A mule ride, an easy way to saunter part-way down the canyon's trails. Don't bother: Packing fancy clothes. The restaurant at the park lodge offers fine dining, but hiking shorts are fine. Don't forget: A jacket. It's chilly at night. --JEANNIE KEVER CAPE COD NATIONAL SEASHORE Every single year, we talk about getting wetsuits. We talk about it, but we never do it. Instead, we show up in late June at the Cape Cod National Seashore in plain old swimsuits. We lug our towels and coolers and toys past the whiteboard scribbled with the morning's water temperature at Coast Guard Beach (or Marconi, or maybe Nauset Light). The kids read it and howl. I read it and howl. My husband, a fish in another life, reads it and laughs. The temperature in this particular stretch of the Atlantic Ocean is ... a whopping 55 degrees. Yes, it is possible to swim for more than three seconds in water that cold, even without a wetsuit. After dumping my stuff on the sand, I approach the lapping waves. A boy skids past on a wake board. A family paddles out on boogie boards. Zen-looking surfers head down the beach. They are all wearing wetsuits. I am not. But as seals nose past in the distance, as gulls swirl above, casing picnics, I shuffle up and nudge my toes into the biting cold. Then my ankles, my knees, my thighs. When my lower body is thoroughly acclimated -- i.e., numb -- I plunge all the way in, head first, and come up laughing. Or am I screaming? Every single year, it's hard to tell. Don't miss: The bike trails. They're all over Cape Cod, including a Rail Trail and a few through sections of the National Seashore. Be warned, though: the one at Province Lands is hilly. Don't bother: Avoid any and all brush or high grass, home to deer ticks (and Lyme disease). It causes erosion on the dunes, anyway. Don't forget to pack: A kite. The beaches are windy. Just don't fly it near anyone's head. --AMY BIANCOLLI BIG BEND NATIONAL PARK Trudging up the trail to the South Rim of Big Bend National Park, you wonder if you'll ever get there. Keep trudging. It's worth it. Carrying packs heavy with water and provisions, our Boy Scout Venture Crew climbed steep switchbacks through rocky terrain, oak forests and the lush grasses of Laguna Meadows before we reached the big payoff. This 15-mile loop offers the best views in Texas. The South Rim looks out over the rugged Chisos Mountains into Mexico. Craggy junipers and straight-arrow agave shoots frame the vista. Falcons nesting among the rocks soar out to over the canyon. The view was so spectacular that our crew stopped to soak it in, hiked over to our primitive campsite in Boot Canyon and set up camp, then headed back to the South Rim to watch the sunset. We also scrambled up the steep, rocky trail to Emory Peak, a two-mile round trip. It's a strenuous climb (worse coming down), but you can see forever in all directions from the panoramic lookout. At 7,825 feet, it's one of the highest points in Texas. Coming down the Pinnacles Trail is another spectacular view -- at sunset, Casa Grande Peak changes color with the sun's rays. Don't miss: The panoramic views from the South Rim and Emory Peak; Casa Grande at sunset. Don't bother: Stopping by the dinosaur exhibit on the way to Chisos Basin. Don't forget: If backpacking, you'll need to carry all your water; a minimum of 1 gallon a day is recommended. This is primitive camping, so everything you pack in, you must pack out. --MELISSA WARD AGUILAR ACADIA NATIONAL PARK Acadia National Park on the coast of Maine may be small at 47 square miles, but it packs a wallop. Largely created and groomed by the Rockefeller family, it comprises most of Mount Desert Island (pronounce it like 'dessert' or you'll sound like a rube), a bit of the mainland and other island areas. It's on the Atlantic coast, of course, but don't expect to take a dip unless you have polar-bear blood. Once, in July, I waded ankle-deep in one of the several natural pools inside the park and thought my feet had been Tasered. Water temperature: 51 degrees. Far better to bike the 27-mile route, clamber up a rock-topped mountain or run and hike on the Rockefellers' many carriage roads. Don't hesitate to wander out of the park, either. Bar Harbor is entirely charming, as are the smaller communities of (very tony) Northeast Harbor and Southwest Harbor, where you may well see a celebrity or high government official trying to low-key it. Don't miss: Sunrise on Cadillac Mountain. Don't bother: Bringing your bikini. Don't forget: Dinner at a real lobster pound. --KYRIE O'CONNOR DENALI NATIONAL PARK AND PRESERVE 'The mountain's out.' So iconic is Mount McKinley to Alaskans that even longtime residents will pause for a glimpse when the opportunity presents itself. At 20,320 feet, North America's highest mountain dominates the state's interior. On a clear day, it's visible from both Anchorage, 140 miles to the south, and Fairbanks, 160 miles to the north -- and beyond. But, especially during the summer, it's usually shrouded in clouds; only one in four visitors will see it. Don't let that stop you from visiting Denali National Park and Preserve. The park's one road is closed to private vehicles past a certain point, but you can enjoy natural splendor and see wildlife in as little as a half day by hiking the trails near the Denali Visitor Center near the park's entrance or with a 30-mile round trip on the free Savage River shuttle bus. If you have an entire day, take a bus to Toklat or the Eielson Visitor Center, Wonder Lake or Kantishna. You can get off whenever you like for a day hike. Or take a guided wildlife tour. Don't let the eight-hour duration deter you; you'll see so many animals you'll forget you're bumping along in a converted school bus. As we rode up to the magnificent Polychrome Pass on one trip, we looked down across the tiaga and spotted a pair of hikers, two caribou and a grizzly bear within a quarter mile of each other -- and all unaware of the others' existence nearby. If you have the luxury of a few days, consider a backcountry expedition. Or, if you're less hardy, stay at one of the wilderness lodges deep inside the park. That way, when the mountain does come out, you'll have a front-row seat to spectacular. Don't miss: The wildlife. Keep your eyes open for movement, not color, when scanning the park's vast expanses and hillsides for grizzlies, caribou, moose or Dall sheep. Don't bother: Running away should you unexpectedly come upon a bear or moose; you're likely to trigger a chase reflex. Instead, act submissive, avoiding eye contact and speaking in a calm, monotone voice as you back away, always keeping the animal in front of you. Don't forget: DEET-based insect repellent and waterproof gaiters for your legs if you plan to hike. Few trails exist within the park. --ROBERTA MacINNIS YOSEMITE NATIONAL PARK On a road trip from San Francisco to Houston, we made a one-night stop at glorious Yosemite National Park last December. Even on our limited schedule, we were able to see much of what the park had to offer. The roads had not yet iced for the season, so travel was relatively simple, aside from my terror on the hours of winding roads with steep drop-offs that you must drive to reach the park. Once nestled inside the park, my boyfriend and I took a couple of well-worn hikes meant for amateurs and enjoyed them immensely, especially the lower Yosemite Falls trail. Visiting in winter means avoiding the throngs of summer travelers; you don't have to walk far to find yourself in complete solitude. Hiking and general nature appreciation was secondary to our primary goal of this stop: seeing the historic Ahwahnee Hotel. Rooms there cost many hundreds of dollars per night, so we stayed at the modest Yosemite Lodge at the Falls, but grabbed a dinner reservation for the Ahwahnee. Once there, we had cocktails in the hotel's grand room before a meal in the stunning dining hall. On our way out of the park, we drove an hour south to the Mariposa Grove of grand sequoias, still within the park limits. There are fewer trees there than in nearby Sequoia and Kings Canyon National Park, but it was easier to get to. The easy, level hike through the towering giants was a highlight on a trip of grand sights. Don't miss: The huge park general store sells everything from groceries to camping supplies to ecofriendly soaps to take home to mom as a thank-you gift for taking care of your cats. Don't bother: With the miserable cafeteria on the lodge grounds. Don't forget: Don't feed the bears, don't go near the bears, don't leave food around so that the bears will be attracted. Bears die because of our poor bear etiquette. --SARA CRESS 