It's actually quicker to see MSH from the Castle Rock/Johnston Ridge VC side via Spirit Lake Hwy. It's a great way to see the crater, the lake, and to get a general view of the destruction.

However, I like the Windy Ridge side better because you're driving through more of the destruction instead of just viewing it from afar. It is actually quite a bit longer of a drive to get there though.

You really need a whole day to do the loop to the east side and up to Windy Ridge. You can do the Johnston Ridge side in about 4 hours (1 hour each way for the drive and about 2 hours or so at the visitor center and viewing). Of course, either of these trips can take longer if you do a lot of hiking but there is no way you can do Windy Ridge in just 4 hours.

I agree. It is a must-see. Probably the biggest must-see in Washington state right now because it changes so much each year.

I need to dig up my photos of our first trip there in 1983 when it was pure moonscape. Scan them so I can share them here. So surreal.