i know everyone's been on edge about what color i would go with for my porch, and here's the winner:
after about two weeks of rain and sun, the white primer looked pretty messed up (colorwise). there were stains from leaves and mud all over it, so i opted for a gray that was darker than the house color. it's a little more blue and lighter than i had expected, but this is only the first coat (it took forever to dry), so hopefully it'll darken up a bit with another coat.