A good idea is to have some personalized bags made for you at home. They can be plastic or cellophane and don't take up too much luggage space. Then buy at Costco their nut mixes, some cranberries and/or some chocolate covered raisins. You can make some nice munchie bags if you don't find at the store what you are looking for.
Since most hotels are all-inclusive they already provide water, beer, chips or chocolates so its nice to put something extra.