Space itself resembles countless other itsy downtown boutiquesL pale grey walls, framed Vogue photos. Niche is tailoring to women's true bodies, with sizes ranging from 00 to 16, and a free on-site tailor to hem jeans while you wait. Brands like Dallin Chase, Cloak & Dagger, Beija Flor, Guido and Mary, and James Jeans abound. Also stocks denim-flattering accessories like the invisibelt, and...