You don't say if it's just you going, or if another adult will be going also. If there are two adults, I recommend bringing two strollers that both recline. I know my 3-1/2 year old took naps during the day at Disney when we went in September. We also had a 1-1/2 y/o with us and had two strollers and were very glad we took both. We then had two baskets to hold things, each child had a snack tray and plenty of room to relax.
Another things is don't spazz out if they don't eat 'right' while you're there. One week of not eating three meals a day will not hurt them. I tried to be sure they ate a nice, healthy breakfast, then the rest of the day was pretty much what they felt like eating. Don't get me wrong, I don't mean candy and cookies all day long, but if they just wanted french fries for lunch, then that was fine. Ice cream has calcium, peanut butter crackers have protein and iron in them, etc. I made sure they took their vitamin in the morning (made ME feel better, anyway).
I put the baby back on formula for that week (he still liked it) so I could bring powdered formula to the parks and just mix it with water (room(air) temperature) and that worked out good. I'd bring bottles with the proper amount of dry formula in them, water, and an extra bottle to measure out the correct amount of ounces of water, and just pour the water into the formula bottle when he needed a bottle. I kept them all in the Zip Loc bags (the ones with the actual zipper worked out much better than the ones you have to line up and press together).
Which brings me to Zip Loc bags -- they worked out great with the little ones. We had peanut butter crackers in one, licorice in another, etc. Extra pacifiers, camera (in case it rained), loose change, etc. We just things in the bags, and put the bags in our backpack, which was stored in the stroller basket -- then we could easily locate things w/o having to dig through everything.
I recommend getting a hanging thing for the back of the stroller so that things like wipes, a diaper, your sunglasses, water bottle, etc, can be reached easily without having to dig through your bag or the stroller basket. I bought one that is made for a car (to put over the back of one of the front seats) and it fit perfectly on the stroller, and even stayed on (and the items stayed in) while the stroller was reclined (which is what I did when we parked out stroller so our 'stuff' wasn't so out in the open).
Sorry this was so long....hope some of these tips help!
Have fun