Cork is my number one choice at the moment. It has to be way lighter than most alternatives, durable, easy to repair whether tile or sheet, natural, flexible etc.
I toyed with the idea of an engineered wood product but it would just tear itself apart in the climate up here.
I'm planning on installing the cork towards the end of the project but I'll see what the samples look like when they arrive. (I have access to a crew who could put a commercial finish down for me so it should be very durable).
1960 Sovereign 33' Pacific Railroad Custom