The best department stores are Matsuya, Mitsukoshi and Wako. Lots of special stores are behind the main street in places where you might never thought you could find them. If you don't have much time to spend in Tokyo, Shinjuku is the place to see. Shinjuku divides into two areas, west and east by the station. On the western side is the highest concentration of skyscrapers and the entertainments.
Eastern side is the most lively part.
Shibuya Young people will definatelaly have to go to Shibuya. Basically, everything you can find for entertainment in Tokyo is stuffed there. The place is Shinjuku for the youngs. If you like Japanese Digital Technologies the place you want to visit is Akihabara. The entire city is only structured by the latest Japanese Digital electronic technology Department Stores.