I have a couple of relatives who are order priests, and they have both paid vacation time and retreat time, built into their employment contracts (one is at a parish, one at a college). As order priests, that salary goes directly to their order and their travel expenses within reason are paid by the order, as are expenses related to retreats. They usually spend the time at home with family, and if there are further expenses (skiing, ballgames etc) the family picks it up for them. One of them used to be a missionary and the order paid for a trip home once every 3 years.
I know other priests who sign up as chaplains on pilgrimages, cruises etc. organized by Catholic travel agents, where all their expenses are covered.