Not all ATV enthusiasts have all family members in sync with ATVing sand dunes. It is a dusty, dirty business, and frankly, sand is not all that a "girl thing." The nice thing about the sand dunes in Washington State is that they are centrally located in a place where there is a lot to do and see outside of the sand area. There are outdoorsy things available, like swimming, hiking, and picnicking. There are indoorsy things also.
The Ginkgo Museum and View Area at exit 136 off I-90 is one of them. This is free to the public and open from May to September. They have a good display of petrified woods. They also have a souvenir shop. Also close by is Ginkgo Nature Area. Here is an interpretive hiking trail system through a prehistoric lakebed. Open daily during daylight hours an ATV group could go and have some fun while the most sedate of the family takes in the natural history.
Frenchmen Springs Coulee at exit 143 is a dry falls left from an ancient flood. Here, daring members of the group can spend the day rock climbing and hiking, while others ATV over the dunes. Exit 143 will also access The Gorge. This is a natural amphitheater that you can hike around, and if you plan your ATV outing just right, you can take in a concert here. These are ticketed events and run through the summer into the fall. Quilomene Creek Sand Bar on the west bank of the Columbia has boating, swimming, and horseback riding. Being an ATV family means there's something for everyone!