I've been painting on wood an really liking it. Perhaps because it's a hard surface, I am able to get thick brush strokes that seem to disappear on canvas. Also, it's easy to sand off something I don't like and re-prime the surface without changing it much. Canvas loses its texture as the primer gets thicker so the paint doesn't act the same way and washes don't flow as well. I use cradled wood panels, meaning that there is reinforcing wood framework on the back of the surface. The sides of the reinforcing wood strips make for a nice edge that doesn't require framing. Framing could be added but it's actually redundant.
I'm doing a number of small still lifes (lives?) for my show. This bag is one of them. For some weird reason, my usual painting procedure has a different appearance when its on wood. I start off with a monochromatic underpainting. I will do a drawing and then build up medium and dark tonal areas. Usually this stage will look great on canvas, but on wood it's not very attractive. Then I add heavier colored areas and it really comes to life. This bag didn't look that great as an underpainting so I was afraid it would be a mediocre painting and then I added the color it was transformed into a piece I really like.