The first thing you need to do before planning your trip here is to check the weather. If it's not sunny and clear, it's not worth it. It's a tall mountain, and any clouds will probably obscure the peak. Another thing to keep in mind is that it's more than 3,000 feet above sea level, so you're likely to need a jacket or sweater if you're used to temperatures above 60 F / 15 C.
There are several viewpoints along the way with good photo opportunities, but Johnston Ridge is the closest you'll get to the volcano without hiking gear. Surprisingly, none of the stops have refreshments of any kind--not even vending machines--so bring food and drink with you. Johnston Ridge's website says they have a food cart during summer, but mid-September is still summer and we saw no such thing.
There is a fee of $8.00 to access Johnston Ridge. That means anything beyond the parking lot. Whether you want to see the film or not, you have to pay. Even just to get a picture at the railing.
The film's content is interesting, but the visuals are poorly produced. The special effects are beneath SyFy movie-of-the-week quality. But you might as well sit through it, because they do the guided tours right after each showing.
There's a long trail off to the east (about a mile of it is visible from the visitor center) where you can go and look at the smashed trees up close. We arrived too late in the day to think about going, but there were several people on the trail. It looks pretty level so it's not too challenging.
We got some great pictures here, so we're not sorry we paid the $8.00 and made the long drive up to the top. But with the drive up being more than an hour, we should have planned to come earlier in the day.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.