My girlfriend and I rode this last Sunday. We had a great ride despite the cold and a bit of rain. This road has plenty for the biker to enjoy: gentle curves to more intense curves but nothing threatening unless you are a new biker then you don´t belong on it.
Of course, the goal is Mt St Helens which is beautiful in itself, but the National Park Service has terrific interpretive centers located along the route. See them all if you can. They are terrific. National Parks as an example of the government can do things right. Take advantage of it.
Only one of the park centers has a cost and that is the one at Mt St Helens. To go in costs $8 for an adult. It´s worth it. If you have sprung the $10 for a lifetime seniors pass, it is free. Of course, you have to be a senior to get it.
This ride out to Mt St Helens and back - either for northbound or southbound riders on Highway 5 - is very scenic and a great road, practicallly *made* for motorcycles. Nice long curving corners, nothing surprises you. A gorgeous ride, and beautiful views of Mt St Helens when you get to the end. Go all the way up to the visitor center and go in and watch the movie/see the exhibits. Incredible place - the volcano is amazing!