I packed a whole bunch of containers full of snacks for the ride and food to munch on while we were there. I used a variety of sizes so that I would have some choices if I needed them (and I did--many times!)
We packed Abby's suction catheters in this one. It's actually a lunch box, but it is a great size for all sorts of things and has a handle. This held 40 catheters.
This divided box was great for some of her medical supplies.
We took a container full of icy water with us to Dutch Wonderland so that I could wipe Abby down and keep her cooler. The L&L box was perfect because it doesn't leak.
Thrifty tip: stay at a hotel with a free breakfast. They almost always have bread and bagels, so bring a jar of peanut butter (ours had tubs there) and make sandwiches for lunch. :)
We brought two different coolers with us because we had a bunch of frozen milk to bring. One was larger than the other, so we used them for different things. This is the L & L cooler bag I got recently, which came in handy quite often. It's smaller than the other one we brought and was a good size to bring with us to the park. It fit nicely on the stroller and holds a lot of food.
Side note: The downside to having soooo many bags on your stroller...that the security guard has to check them all! I'm pretty sure we had some people annoyed with us as we opened our 15 different bags and then had to explain that it wasn't a bomb-making kit, it was a suction machine. :) One security guard took one look at Abby and just waved us on through.