The Columbia River Gorge is known for its stunning waterfalls. It's less than an hour away from the house. Click through to a map of all of the waterfalls, including ones that are an easy walk from your car vs. ones that are a hike.
If you only want see hikes that are an easy walk from your car, uncheck the box on the left of the map that says "waterfall hikes" so it'll only show you the "accessible by car" waterfalls on the map. This is a great option if you have young children.