The most amazing thing I ever saw was a launch out of Vandenburg in '86. I was driving the Angeles Crest Highway about forty miles out of Lancaster one evening about one hour after sunset. Out in the western sky, a giant glowing green orb appeared, in the middle of which was a pinprick of white light, heading up and westwards. (This was the rocket exhaust plume.)
With no way to measure the size, (scale), of the exhaust residue, I pulled off to the side of the road in my '65 Ford, completely gobsmacked. I had no idea of the scale of the vision in front of me. (I actually considered finding some local to verify I hadn't lost my marbles). No one lived on the road nearby, so I had to wait until the next day to find out about the launch, after over half of LA had completely freaked out over it and had called all the radio stations.
A green glowing cloud in the upper atmosphere, with a whitish glowing pinprick rocket exhaust, moving westwards fast.
Amazing.
Never seen anything like it, probably never will again. The funny thing is scale was never an issue; there's nothing you can compare it to. It's otherworldly, quite literally.