if you want other wood that'll take decades of abuse and weather exposure w/ no finish necessary, try eucalyptus - might be hard to find good planks of it tho' as it's used for so many other things - I happened on a long 2½ x 8" piece when I was looking for something for the bed boards on my apple elevator/washer, and it's had heavy stainless paddles draggin apples on it for over 20 years, no finish applied - looks pretty much how it did in the beginning, and dries within minutes of the water turning off
Bill