Chesterfield Topcoat

AMI Single Breasted Topcoat, 
Buy It Now at Barneys, $419
Uniqlo Chesterfield Coat
Buy It Now at Uniqlo, $150 

A long topcoat like this ups your style game, since it's normally worn over suits. That isn't to say you can't rock it over a pair of proper wool trousers and your favorite denim jacket either. Cop one in an of-the-moment camel color or a darker charcoal. Both are equally versatile. The length has an added bonus: it'll keep her legs warm when you throw it over her while you're hopping from bar to bar. You are offering her your coat right? Be a gentleman... for the first few shots, at least.