Cannas come in dwarf and tall varieties. The tall should be perfect for you. You can get a lot of different colours and patterns in the leaves as well as flowers. They can provide all year colour and look very tropical.

I doubt if Cannas would be tall enough. Why don't you try the Lombardy or Pencil Cypress. It is tall and extremely thin and doesn't look bad in a tropical setting. Good luck.- Ian.

How about a vine? You could attach any needed supports to the fence.

Sorry, don't know your climate to offer specific suggestions. Around here, the fence would be covered in 6 months, even if you didn't plant anything.