Lord of the Rings is always great, but they're pretty long, especially if you go for the extended versions.
Terry Gillam's stuff is great, if sometimes pretty out there. You could try Time Bandits or The Brothers Grimm.
You also can't go wrong with the classics, such as Princess Bride or Willow. Willow also has the bonus of the titular character being played by Warwick Davis, who plays both Professor Flitwick and Griphook in the Potter films.