Great cuisine in Taipei!
Taipei's highlights are its nightmarkets and cable car, maybe the temples if you are interested. Taipei 101 is just ok, something to tick from your checklist but not such an experience. Interesting to know more about the engineering design. There are lots of shopps on the observation desk tailored to the avid mainland Chinese shopper. You'll be better off hiking and seeing the city at night from one of the hills surrounding the CBD, they are really easy hikes, so keep the expectations low.
Insider Tip:Go East and explore Hualien and Toroko National Park, the South West cost is also nice, Kaohsiung city is worthy a visit.