We did World of Gin on our Dream cruise a couple of weeks ago. It was really good, and significantly less expensive than World of Old Fashioned ($60 v $100). It was held in Meridian at 10PM. We got lots of extra tastes of things, with some very creative cocktails including ending with an awesome chocolate/orange twist Negroni. It seems to very much be at the discretion of the bartenders as to what they serve, so will likely differ from ship to ship.