I would say at a bare minimum, have your hotel name written/printed in Chinese. Most taxi drivers won't recognize the English name of your hotel, which generally sounds nothing like the Chinese name. Of course, if you're staying in Changsha near the metro line, it's generally easy enough to navigate yourself back to a metro station, but if you ever need to ask for directions or jump in a taxi, it's good to be able to convey where you need to go!