Two experiences:
First one: Have you ever been on manta with a row of porcupines? Yeah, I thought so... 
Second one: About 8 years ago, I got on Spider-Man. it started out fine, but when we got to the warehouse scene, it just stopped. The Emergency lights kept going on and off. the car would move about a scene at a time (With all effects and screens working, off time, and no sound), and then just stop. It was the first time I got to see just how effective "squenching" is.
The sad thing is, this was before I was the theme park geek I am now. I started to freak out (claustrophobic) when It would stop. I don't remember as much as I would like, but I still think it was awesome experience.