oh the birch sweater works with all sorts of things. i think because the sweater is so classic and borders on preppy that i like to wear it with non preppy pieces. case in point: the 'barrie' pants. aka 'coolest pants ever'.
the barrie's crazy long zipper means you can wear them high or low depending on your mood. the flat front and elastic waist back make them the coziest pants to wear. hello travel pants! i suggest taking your normal size or if you don't want to wear drop crotch then size down.