cardigan (Loft from last fall, similar) / top / pants (Loft from last fall, similar) / oxfords (sold out, similar)
There are some trends that I will never let go of, even when the term 'trendy' doesn't apply to that piece of clothing anymore. I think I'm solidly on the Birkenstock train for good (see also: stripes, florals, lace, and flats).
My biggest go-to (some may call it a uniform) during a busy work week is definitely the cardigan. Usually, the longer I can get that cardigan, the better. I think once upon a time it was called a 'grandpa cardigan', I prefer to class it up and bit and call it the 'stylish-older-lady-who-prefers-to-have-warm-arms cardigan'.