There are different types of tours that cater to various culinary interests and experiences, so you can be sure there will be one that the whole family will enjoy.
Whale watching is one of the activities that are great for families, and many companies in the area provide tours daily, such as Island Adventures Whale Watching.
Olympic National Park, North Cascades National Park, and Mount Rainier National Park are all easy to get to from Seattle and offer hiking trails and more at different difficulty levels.