I think the .ws would sell for a decent amount if it is a really famous location. So dublin.ws, paris.ws, newyork.ws, toronto.ws ... I would reg those if they'd be available. But I would not do the .ws of a lesser known city like valladolid.ws or littlerock.ws
Also, don't expect sales as high as the .com version or .info version. But still, you don't really believe nobody would bid a decent amount for domains like moscow.ws or washington.ws ?? Maybe a lot less than the .com variant, but still a good sum of money.