hi i am visiting tainan in october2014 , for a 5 days business trip. just have 1 full day & 3 nights

As u will have three nights, I would suggest you enjoy yourself at local night markets. The Xiaobei Night Market and at Lane 174, Section 4, Ximen Road and Wusheng Night Market at Lane 69, Wusheng Road, Zhongxi District are highly recommended. For your one-day trip, you can go to Fort Zeelandia, Anping Tree House and the foreign firms there.