S!
FWIW, it's not really a Holy Sh1t! experience, but in my real-world flying, one thing that gives me the shivers is popping above an overcast layer to find myself between two 8/8 layers. It really is the most otherworldly experience I've ever had.
You might also consider adding in the brocken spectre, which I've been fortunate enough to see on a few occasions:
I can appreciate that it probably wouldn't be too easy to get the effect just right though.
You might also consider the
green flash, I've never seen it, but I'm told it's spectacular from 30,000 feet.
W.