On top of the W hotel, you can find the Yen bar, with a nice view over Xinyi area. The bar is really small, so you better come early. The place is fancy and trendy, and the cocktails quite good. I tried the Ms W with truffle infused vodka, rose, vanilla and champagne (if i remember well). Quite pricy (it starts around 600NTD), but the bar is nice and you have free refill of sweet potato chips. It’s a good option if you want to go to clubs after.
34th floor (i think)
W hotel in Xinyi area