Nobody ever comes in asking the easy questions. Art Nouveau + high fantasy is a piece of cake, but Deco is tougher.

Trouble is, high fantasy usually implies a hand-crafted look, and Art Deco is all about that regimented, mechanical appearance. If I were making a map in what I imagine to be a synthesis between the two, I'd go for one of the tall, arching typefaces that still have a bit of the Nouveau heritage. Maybe something like Plaza. It's heavy on the mechanical end of things, but I think it still looks like something an elf would appreciate.