http://www.cp-sandiego.com/
Not exactly strange, but I really like this design. It may or may not be original, but it is to me since I've never stayed in a hotel like it.
The way it works is it technically has no walls. Each room is walled in, but the hotel itself is open to the air: the doors to outside the hotel are open most of the time(my only concern due to security), and when moving between structures, there are no doors. You simply move about the hotel and can enter/leave each building within it without going through doors. It's all open to the air.
The hallways connecting rooms are open to the air as well; they are open to a giant "courtyard" of sorts spanning all the floors. The courtyard is filled with waterfalls and pretty much overgrown with tall trees and plants.
There's no ceiling in the courtyard either. It was quite a surprise to look up and see none. It was also quite nice; it gives a natural feel of a sanctuary and haven to the courtyard. A piece of nature intertwined with civilization.
The structure itself is unique, too. The floors aren't level. There were eight floors in the building we stayed in. But, each side of the floor was at a different height, so, one side of floor 7 would be midway between the other side of floor 7 and floor 8. On the edges, they were connected via stairwells, and in the middle, they were connected by a platform that would connect to both sides of a floor for all 8 floors.
The elevators themselves were made with glass backs so you could look at the courtyard as you rode them.
Overall, it was quite pleasant.

Best hotel I've ever been in; and it's cheaper than far less aesthetically-appealing hotels!