I´d second Gonative opinion, if possible rather go to Toyako. The Onsen are natural and the Area is nicer than Noboribetsu. The walk through the ruins are really special if you haven´t seen natural destruction of houses and streets before. When i visited there was a nightly firework at the lake as well. Noboribetsu seemed very artifical to me and it is a bit aged.
Here are my 2 webblog-posts with pictures to
Noboribetsu and
Toyako.
The pictures from noboribetsu are all inside the Town or in walking distance. In Toyako i haven´t stayed directly in the city but the surrounding Area is great, however i´d recommend to rent a car in Sapporo for this day trip ( the destroyed are is a bit outside).
For shopping in Tokyo: Have you thought of Kichijoji? Its the are mosz of my japanese friends recommend and i did like it alot. There are no real speciality shops like in Harajuku but it still serves a young and hip crowd.
Firebird