We always order with GG and we really only need the water for WDW but order the rest to bring home
Our must haves are
48 bottles of dasani water
clorox wipes (in case someone is ill - a good trip is when we dont need them

)
washing up liquid to wash up our refillable mugs
wet ones individual antiseptic wipes - use them before eating in the parks and then bring them home where I use oodles at the school I work at.
Ziploc sandwich bags - for carrying stuff in the parks - I always put items such as cameras and passports in them before I go on water rides etc.
Then the not so must-haves
rice krispie treats - the strawberry and chocolate drizzle ones we can't get here go in packed lunches for weeks

domino cinammon sugar - for pancakes at home
cornbread mix
ranch dressing mix
famous amos cookies - DD favourites
the mini pringles packs - the cheddar cheese ones are addictive
we usually find that even with delivery and all the extras of the USA brands we love we still spend less thna the water would cost us at $2.20 per bottle in the park

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