Snow White, if nothing else, always cracks me up at the end. You're right in the action, the dwarfs are cornering the evil witch, lightning is flashing and....surprise! The rides over. All you get is a sign on the wall that says, "And they all live happily ever after." The imagineers ran out of room when building the ride. In my opinion, its the best part. The element of SURPRISE!
The "must see" dark rides at DL's Fantasyland are Mr. Toad, Alice in Wonderland and Peter Pan, in my opinion. Unfortunately, Peter Pan always has a long line up, so go first thing in the morning. As for Snow White, I find that ride scary, and I'm 42 (that's what I like about it). It does end way too abruptly, but it's good while it lasts.
Mr. Toad's is a jolly ride, this is where you will want to take your 20 yr-old friends. Also good for a laugh; while waiting in line, there is a large mural of Dover and surrounding areas and it looks like the Judge is whispering into the Horses rear end!