All the hotels I asked in China last year had adapters. But, they are not always so well made and the effort to enable the adapters to fit many kinds of plugs may lead to problems.

When I plugged in my laptop in Shanghai I blew every fuse on the floor. The adapter was given to me by the hotel, but was not a good fit. I had the best luck at Coffee Bean and Tea Leaf cafes. Free power, free adapter and free wifi. Good breakfast deals too. And, no blown fuses. ^