I like the Troll in Seattle, Mt. St. Helens, Leavenworth, the Olympic peninsula, the San Juan Islands.....
From the Smithsonian website:
Washington - Landmarks and Points of Interest | Washington | Smithsonian Magazine
Historic structures refurbished and enhanced with modern amenities can be found in the striking locales of many Washington State Parks. These landmark buildings include the lantern room of a lighthouse, a log hall, a chapel, a converted theatre and a granite shelter at a mountain summit.
One notable patch of hallowed ground is Steptoe Battlefield, near Rosalia in Eastern Washington. It was here in May of 1858 when the Indians claimed their final victory over the United States Army. A 25-foot monument commemorates the battle.
For years, the massive Admiralty Head Lighthouse held vigil over the entrance to the Puget Sound. Today it offers visitors the chance to check out the historical coast artillery post and sweeping views of the Strait of Juan de Fuca.
Embodying the heartbeat of downtown Seattle, the 74-acre Seattle Center has played host to the city's largest festivals since it opened for the 1962 World's Fair. Today, it serves as home to the Space Needle, Pacific Science Center, Children's Museum, Seattle Opera, Pacific Northwest Ballet, Experience Music Project the NBA's Seattle Supersonics and the WNBA's Seattle Storm.
A unique and futuristic structure, the Space Needle has become a Seattle icon and a favorite for tourists. Standing 650 feet in the air it affords visitors the chance to glimpse Puget Sound and the Olympic and Cascade mountain ranges from a birds-eye view. In just 41 seconds you're at the top, 520 feet up, beholding a breathtaking 360 degree view of the city and a towering panorama of Washington's spectacular natural wonders.
Near the top of fashionable Queen Anne Hill in Seattle, Kerry Park, long a favorite of amateur and professional photographers alike, offers a full view of Seattle. The Space Needle rises at nearly eye-level a ?-mile away, while Mt. Rainier provides a backdrop that appears to be a double exposure. Sailboats, ferries and the Olympic Mountains fill the view to the west.
The 20-acre Kubota Garden in Seattle provides an urban refuge with waterfalls, ponds, rock outcroppings and gorgeous gardens combining Northwest and Pacific Rim styles.
Seattle's Fremont neighborhood is an eccentric and artsy district that is home to some of the city's best-loved and "interactive" public art. Among them are "Waiting for the Interurban," an imported 16-foot bronze statue of Vladimir Lenin and the whimsical, public sculpture of a shaggy haired creature (the Fremont Troll) with an old style Volkswagen beetle in his grasp lurking under the Aurora bridge since 1990. Come visit these works of art and pose for a picture. While there, you can visit vintage clothing shops, tattoo parlors, brewpubs, and art galleries that line the walk, offering a diverse selection of national and regional contemporary art.
In a city filled with architectural marvels, many have claimed Seattle's Central Library, opened in 2004, as the most imaginative and distinct structure. Designed by a Dutch architectural firm, the striking, silvery 11-story metal and glass figure dazzles visitors on either side of its 1.45-million volume collection.
Other man-made marvels are honored at Kent's Hydroplane and Raceboat Museum, the only one in American dedicated to powerboat racing. Paying homage to the region's maritime and boat racing tradition, the collection features hydroplanes spanning seven decades, including boats that have won 17 Gold Cups.
Washington is home to another novelty museum, the World Kite Museum in Long Beach on the state's coast. Now in a new 10,000-square-foot building, it's still the only American museum dedicated to kites, kite makers and famous kite fliers.
A reminder of the early farming industry, the three-story Barron Flour Mill in Eastern Washington's Oakesdale, has withstood the Depression, and the advent of supermarkets. This flour mill continues today, supply the finest flour to a broad spectrum of people, ranging from rural communities to the finest organic diners in New York.
The self-proclaimed "Antique Capital of the Northwest," Snohomish, north of King County, is justified in its title, with 450 dealers offering their wares within five blocks. Astride a river carrying the same name, Snohomish itself feels collectible, with an array of historic Victorian homes, a turn-of-the-19th-century village, and gardens around town.
Paying homage to Washington's state flower is the Rhododendron Species Foundation and Botanical Garden in Federal Way. One of the world's largest rhododendron collections, this site boasts more than 10,000 rhododendrons in a brilliant array of colors against a 22-acre backdrop of native conifers.
An unusual roadside attraction, Ex-Nihilo (also known as Recycled Spirits of Iron), has been turning many heads en route to Mount Rainer. This 4-acre outdoor gallery features sculptures created from recycled iron and driftwood by artist Dan Klennert.