Varies from place to place. Like every other location (supermarkets, car parks, etc.), some are free and some aren't. Speeds and costs per kWh vary as well. Access is variable too. I know of one hotel round these parts that reserves chargers for residents only behind an electronic gate; a few miles away there's another hotel where you can just park, plug in and drive away later with your free volts, without even setting foot in the building itself.