The Haunted Mansion extended queue is definitely worth walking through, it's fun to play with the stuff as you walk by. Hint: touch everything.
The Soarin' queue has a "video game" that can be played by the crowd using the screens that show the Eyvind Earle-esque landscapes. In my experience, it isn't running often - the queue has to be long, pretty full, and the crowd at a relative standstill for it to work very well. We've actually tried to get in when it was being played before, and we've only managed it twice in all the years Soarin has been opened. It was fun. The last few times we've stood in a long line for Soarin it wasn't running. Very hit or miss.
The Ariel ride queue's game is fun. And Pooh, etc.
BTMRR has some interactive stuff now, and it's cool but not as obvious. There are plungers you can use to set off stuff in the ride, and viewers where you can see vignettes. You have to look a bit harder for the things in this line, IMHO.
There is also some interactivity at Epcot - Test Track allows your party to customize your car for the ride, Spaceship Earth allows you to customize some preferences on a video screen in your vehicle.
Haunted Mansion is my favorite, but I suspect the guys in my family like Test Track's car customization best.