There are so many great examples of UI design in Final Fantasy - The Spirits Within and they encapsulate a wide range of interfaces including holographic diagrams, medical instruments, military maps and HUDS.
I was so impressed by the quality and detail that went into the interface designs. Everything seems to be so well thought out that even the buttons on the keyboards are stylised.
I particularly love the look of all the frames and panelling in the displays. They used so many interesting shapes to hold up and contain the information and visuals, which creates a look that's intricate, futuristic and visually striking.
It's also worth mentioning the amazing job they did in animating the interfaces, which added another dimension to the designs and really brought them to life, not to mention the sound design on top of that.
When it comes to interface design especially for fictional interfaces, you really need the whole package to make it believable. You need great layouts and designs, as well as convincing animations, and complementary sound design.
If you get those three ingredients right you come out with something as impressive as the work seen in Final Fantasy, something that you can immediately relate to and understand to a degree what an interface is actually doing, which makes it believable.
And I think that's what Final Fantasy does really well.
I was surprised by the amount of examples there were in the movie. So there's plenty to see and inspire you.