For wildlife, for birds anyway, I found that printing on canvas was not a very good solution. I like to capture detail, and when you print on canvas your are literally obliterating that detail.
I was one of a small handful of photographers in a themed mixed media gallery show fairly recently, there was one other guy with some bird photos and he'd chosen to print them all on Canvas. Frankly I found that his work was really damaged by this printing process. It just ended up looking like a gimmick, and the prints lacked the detail that people expect when looking at wildlife shots.
I am sure there are exceptions, where masses of color etc., will make for a nice composition. In fact I saw exactly that sort of exception at another gallery show I was part of. The best work there was this local guy who'd been shooting underwater photos of jellyfish. The lighting and color printed on canvas was in fact spectacular. The least "exotic" species in the show, the most local (read easy to get to) locations, and yet the most artistic "best of show" results.
Metal is a whole different story!
I've not seen any wood prints.