Very late notice, but there is a festival in Sanjhih today and tomorrow. You can enjoy family activities, food, great scenery, performances... from 10am until 8:40pm Saturday and 10am until 5pm tomorrow.
Sanjhih is just past Danshui. Too bad the weather is not so good this weekend in North Taiwan
Official Site (Chinese) http://www.sanjhih.com/index.html