what I always do,with my girlfriend, is bring a suitcase full of snacks:things for breakfast and maybe something a little bit heavier for when we go back and relax at the hotel. then we use that same suitcase for stuff that we bought inside of jamming it into an already full suitcase.
I always have 2 cameras, enough contact solution, a mini deorderant for after splah mountain, a mini pin holder(because those lanyards hurt after a while), a magazine or two for the plane ride, asprin, sunscreen, something to wear in case it is cool out, a full itenary that goes out the window once we get there, my ID so I can have a few while walking through the WS, quaters for the arcade at Pop Century-they have an awsome Star Wars game and an enclosed flight game.