I recommend Yandang Shan and Jiangxinyu Park.

Alas. Wenzhou is not a place to go sightseeing. Rather do business.However, you might want to see Yandang Mountains, that present a fantastic view in twilight, and Nanxi River, rapid and fresh, with old countryside, fresh seafood, and bamboo rafting. In Wenzhou itself you can cross by ferry to Jianqing Island with lush greenery, peaceful ponds, and a good angling facility. They can cook the fish you catch for you. Night life is boring, with endless KTV (karaoke) everywhere.