I've never been on Rock'n Rollercoaster...don't know why, I'm just too chicken.
As for Tower of Terror, I used to be able to ride it back to back but now, it scares me. I have to say that the best bit about it is riding it in the dark and looking all around the park. I always used to enjoy queueing for it, then when finally getting told to sat and seeing all about Sally Shine and the four others who disappeared that night and then WHAM! the drops begin. *shudders* I prefer the movie these days. x