Hi,
I used a fairly hard shelled suitcase for all of our snacks and food. I was concerned about our pull-open cans popping open during the flight, so I put those in a zip-lock bags too. My DH was irritated as he helped me pack it. I had wanted to secure the food better: loose snacks etc..., but he impatiently threw everything in there and said that if security wants to they would open up each bag of chips, snack cookies etc...What a crock! It
didn't happen, and I even found a notice that my bag had been inspected at the bottom of the suitcase, so they had been through it and nothing was damaged or opened up. He didn't come with us this time. Thank God! We would have been eating out every meal as he's into this perceived convenience thing: like spending a ton of time at the restaurants and $$ could replace eating a quick, but good breakfast in your hotel room. We had a lot more time to spend at the park, plus money left over!!
Instead of packing little boxes of cereal (great idea and necessary if everyone eats different brands), I just packed one large, unopened box. A sceptical friend also frowned upon the idea of bring a suitcase of food/snacks. She said that with my planned 30 minute stop, I should just buy it there since there's no tax on food in Florida. I'm so glad that we did pack up a suitcase as the 30 minutes was used to purchase milk, fruit, yogurt etc... , and will definitely do it again. It's not easy handling grocery bags during check-in. We brought snacks to the park too, and saved time and $$ again. Of course, we also ate at a few Character meals and counter service at the parks.
If you have a small suitcase, I would use it rather than the duffle bag. Everything would stay neater in a suitcase too.
I didn't pack any laundry detergent, since I didn't expect to do laundry. I would bring a small, unopened box of detergent and keep it in a ziplock bag incase they do open it. I will be anxious to read other posts about this too.
Best Wishes!!