Thanks for the replies. I have been to Taipei many times and didn't believe there was much near TPE. However, I am always willing to learn from the experts. I was there in April and don't want to run into the city just to do the same stuff. However, if I am missing good stuffs near the airport, I would make amend.

While waiting for the replies, I found out Taiwan Travel Bureau provides a morning and an afternoon 4 hour tour for passengers with long enough layover. The tours don't sound exciting but they will give me a different prospective to the city. For those who have sufficient layover time. Here is the link.

https://eng.taiwan.net.tw/tour/index.htm