Personally, I think a hybird dark-ride/coaster is a great idea, but I don't really care for the dwarf theme (again, considering that Snow White is right there).
I think maybe a Sleeping Beauty theme, where you fight the dragon, etc ... but could be too close to the fore-mentioned Dragon coaster at Legoland.
My thoughts on a theme:
Beauty and the Beast:
Begining Dark Ride Portion:
The beginning of the story, Belle in her "Provincial" town, journey to the castle, etc, etc, etc. Ending where Belle and Beast get in the fight and Belle runs off into the woods with the wolves.
Belle's pursuit from the wolves and Beasts subsequent rescue.
Ending Dark Ride Portion:
Belle and Beasts falling in love, attack on the castle and Transformation/happily ever after.