From what I remember, Shinjuku is simply full of department stores, which are for the most part are just clothing (unlike North American department stores which include housewares, electronics, toys, etc). A lot of these stores pack higher end merchandise which I think would be of interest to forum members. Shibuya itself seems to cater more to a younger crowd, but there are two main drags in the area that have a lot of higher end stores (not sure if they are mostly geared towards women, though) - Omotesando and Aoyama Dori.
Do search out some locations of Maker's Shirt. This is the Japanese name of Kamakura Shirts and instead of paying $79 USD a shirt you'll pay (at current exchange rates) $51 US a shirt.