Figure out how much you want to spend on the kids souvenirs and purchase Disney gift cards for that amount. Once the card is empty, souvenir shopping is done. Also, save souvenir shopping for later in the trip. Many of the shops carry the same items and most stuff can be found in Downtown Disney. By the end of the trip, you'll know what trinket the kids can't live without. If your kids are young, buy Disney products before the trip then have them magically appear in your hotel room while you are in the park. The kids will love getting special gifts from Mickey, Cinderella or whoever. Take those flavored drink powders for water bottles. The water in the park has distinct flavor that some may not like. Don't spend money on water. Most snack counters and quick service restaurants will give you a free cup of ice water. Take a pocket charger or extra battery for you cellphone. The Disney World apps are good but will eat your cellphone battery. Pack lots of hand sanitizer. Use it often.