I have been evacuated from Spaceship Earth twice, Mission: Space, Toy Story Midway Mania, Dinosaur, and at DCA, Monsters Inc.: Mike & Sully to the Rescue!
Both SSE evacuations were from the Descent portion of the ride.
After starting and stopping a few times in 180 Top, we came to a stop in front of the Virtual Classroom scene (this was in the Jeremy Irons era). The music turned off, the lights turned on, and eventually we were walked down the stairs along the ride track to a door near unload.
The second time I was evacuated from SSE, the ride stopped while we were at the bottom of the ramp while our car was in the process of rotating back to forward. That was a really short walk to get out of the ride. Nothing too exciting.
On Mission: Space, we were halfway through the slingshot around the moon when suddenly the ride stopped. The monitor stopped showing the ride film and had some sort of screen saying something about ISTC training something or other. It took a surprisingly long time for the ride to stop spinning. When we came to a stop, the capsule was not level (the capsule was tilted when the ride video stopped because the ride was entering the lunar gravity assist turn.)
Anyway, we sat in the dark for a while, and eventually we could hear the ride capsule being manually rotated to be level. It was a weird sensation.
Eventually, the ride capsule door was open and we stepped out of the door down a ladder to the bottom of the big circular pit under the ride. We used a different ladder to get out of the pit. It was a really cool experience.
When I was evacuated from Toy Story Midway Mania, we were either at the plate game or the ring toss game, and the game stopped. All the point values went to zero (like the ride does when there is a short delay) and we continued to play the game. Eventually, the game stopped too and the lights came on.
Eventually, we were escorted out of the vehicle and were instructed to follow a path on the ground and out through a door to a hallway that lead out to the Pixar Place restroom area. There wasn't much to see, honestly.
The most recent ride evacuation I had was on Dinosaur. During the 'They're not going to make it!' scene, the ride stopped and the lights went on. It was really cool, there was bare-looking scaffolding with camo netting over it and weird ducts attached to them in a haphazard-looking way.
A rider in the back row figured out that his seat belt was unlocked, so he unbuckled himself and jumped out of the car onto the track. We yelled at him, so he stood next to the car. I think he was yelled at over the PA system, but I am not sure. Eventually, a CM walked by with a stool and a flashlight. We were helped out of the car and walked along the track back to the station.
The floor of the ride track was weirdly sticky. Also, one of the ride vehicle tires was on the other side of the track slot. Is the ride vehicle supposed to do that?
The time I was evacuated from Monsters Inc, the ride stopped in the door room scene near the end of the ride and were walked back to the unload area. It was interesting, but there wasn't much to actually see that you don't see from the ride.
Getting evacuated from a ride is one of my favorite things to get to do at a theme park (if it is not my first time through that ride.) While I was a ride operator, it was one of the most exciting things to get to do (also the hardest thing to do) during a shift.