This is a great sunrise location because the rising sun imparts a beautiful alpenglow on the mountain when it is visible. That’s the tricky part, when it is visible. I tried three consecutive mornings for the shot. The first morning was cloudy; the second morning was foggy at the pass (but clear elsewhere). It wasn’t until the third morning (the day we packed up camp), I was able to capture the sunrise in all its glory.
Another feature of Mount Rainier favored by photographers is that the mountain often forms lenticular clouds. Such clouds can dramatically add to a sunrise (or sunset) shot, particularly if there are no other clouds around to break up a totally blue sky. Such was the case that third morning. In fact, there were two separate lenitcular clouds over Rainier that morning, delighting myself and the, perhaps, 10 or 12 other photographers there.
As you can attest by the photo above and below, I think it was worth getting up a 5 am to drive to the pass by sunrise at 5:30 am to capture this scene.
Sunset shots at Chinook Pass are a more iffy proposition. Because the mountain is west of the pass, you are not guaranteed a good showing of alpenglow. Instead, much depends on the clouds and how they light up. I did try for one sunset shot at Chinook Pass on the trip; the result is below. This shot was taken from above Tipsoo Lake, right next to the highway. Though the sunset was lackluster, luckily there was a lenticular cloud present that gave a bit of color. I captured this image the evening before the sunrise shots above.