We stayed in Shinjuku on our honeymoon, in a tall building with ‘Microsoft’ on the side, in front of a Dunkin Donuts, Eddie Bauer, and Starbucks. Thought we flew 12 hours and landed back in Seattle.
Across the train tracks was the Tokyu Hands. My favorite display had about nine hundred kinds of nail clippers, in prices up to $200.
Shibuya is well-known for youth and energy. May I also recommend getting off the train at the Harajuku stop (before Shibuya on the…um…Blue line?), and walking down “Street of Hell” or Takeshita-Dori, which is ground zero for the Gothic Lolita look. From there you can wander around Harajuku and then back to Omotesando. Omotesando is a wide pretty boulevard with high end retail for blocks and blocks. The Tadao Ando designed Omotesando Hills shopping mall is there, ride the escalators and look at the cool light show, and on the top floor is a very fancy ramen place, usually with a line, but very very good.
Then you can cross Omotesando and onto Cat Street. Cat St is a narrow, might only be pedestrian, collection of retail, sport (Nike is there, awesome concept store/building, also Patagonia, and cool Japanese-only sport lifestyle brands). Cat St will take all your money and then deposit you near the ‘scrum’ in Shibuya.
So so so many amazing things to see, everywhere, all day in Tokyo.