Easiest TIG Pine Treatment

[thinkxingu]

Hi All,
Two summers ago, I put up a wall of tongue-in-groove pine on my camp porch, but I've not yet treated it. I was going to do urethane, but I'm wondering what the absolute easiest/longest-lasting treatment would be. On moist summers last the last one, we sometimes get mold/mildew on wooden surfaces, so I know I'll need to clean the boards with a solution (bleach?) before treating, but any tips are welcome.

Thanks!