While Washington doesn't have a major amusement park to attract families, it does have lots of great, child-oriented museums in Seattle, a park full of fun attractions in Tacoma, national parks, and an active volcano (how cool is that?).
Days 1 & 2: Seattle
Spend the first 2 days of your trip exploring the kid-friendly attractions of Seattle. On the waterfront, visit the Seattle Aquarium and go for a boat tour. At Seattle Center, originally built for the 1962 World's Fair, you'll find enough cool attractions to keep kids of all ages busy for a day or more. Depending on their age, kids' favorites include the Space Needle, the Children's Museum, the Pacific Science Center, the Experience Music Project, the Science Fiction Museum, a small amusement park, and the Seattle Children's Theatre.
Days 3, 4 & 5: The San Juan Islands
From Seattle, head north to the San Juan Islands, home to orca whales and bald eagles. With their beaches, state parks, scooter rentals, and summertime whale-watching tours, the San Juans have long been a favorite summer destination of Washington families. Visit the Whale Museum and the San Juan Island National Historical Park on San Juan Island, and Moran State Park on Orcas Island. If it's summer, go out on a whale-watching cruise. The San Juans are also a great place to introduce the kids to sea kayaking; many tour companies here will take the whole family out on the water.
Days 6, 7 & 8: Olympic Peninsula
If you've brought along passports, you could travel from the San Juans to the Olympic Peninsula by way of Victoria, British Columbia. Otherwise, head back to Anacortes, drive south to the Keystone ferry landing on Whidbey Island, and cross over to Port Townsend on the Olympic Peninsula. In Olympic National Park, visit Hurricane Ridge, Sol Duc Hot Springs, the beaches near La Push, and the Hoh River Valley rainforest. At Hurricane Ridge, you're likely to see nearly tame deer. In the Hoh River Valley, keep an eye out for elk. Spend your last night on the peninsula at a lodge on Lake Quinault.
Days 9 & 10: Mount Rainier National Park
From Lake Quinault, drive to Mount Rainier National Park. En route, stop at Northwest Trek Wildlife Park, a drive-through zoo filled with wild animals from around North America. At Mount Rainier National Park, wander the wildflower meadows at Paradise, visit the 1,000-year-old western red cedars at Grove of the Patriarchs, and look for mountain goats on the trails at Sunrise.
Day 11: Mount St. Helens National Volcanic Monument
You may not see lava pouring down the side of the volcano, but since late 2004, Mount St. Helens has been spewing ash and smoke, and a new lava dome is building in the crater left by the volcano's huge 1980 eruption. Although operated as a sort of promotional facility for the logging industry, the Charles W. Bingham Forest Learning Center has a playground and hands-on exhibits. At the end of the day, drive north to Tacoma to spend the night.
Day 12: Tacoma
Tacoma's Point Defiance Park is one of the best places in the state to bring the family. Start at Point Defiance Zoo & Aquarium and then visit the Fort Nisqually Living History Museum, where interpreters dress up in 19th-century fur-traders' attire. At the Camp 6 Logging Museum, you can hop aboard an old logging train. The park also has lots of hiking trails and good waterfront restaurants nearby.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.