What sort of outfit would go well with this jacket/peacoat/blazer?

Dark faded jeans, if you've got thin long legs then go for a skinny cut. If you've got chunky thighs, then a flare cut will make you look thinner. For winter, a cute pair of black leather boots (or even Uggs) worn over the jeans would look cute. For a spring look wear a bright pair of flats to give the outfit some color. A scarf in any solid color would work. As for the top, a nice collared shirt or solid colored long sleeve thermal would give you a nice casual but polished look.