Hello!
I really can't answer anything about OKW, as I have never stayed there. But as for the park bag, I have a few suggestions!
1. I would definitely bring sunscreen to the parks every day, even if it isn't sunny. It is very easy to get sunburn, especially on your face, and when that sunburn strikes boy is it uncomfortable!
2. If you are planning on riding the water rides (which I highly reccomend) It would be a good idea to bring a big plastic bag to put your whole backpack/drawstring bag/purse inside during the rides. The floors of the water rides tend to get VERY wet, and you don't want your electronics getting exposed to the water. One of the big Disney bags works like a charm, and you can ask for one at any merchandise shop.
3. Bring some snacks! I know part of the fun at Disney is trying all the different foods and dining experiences. But with all the walking, you may tend to get low blood sugar. I always pack granola bars, fruit snacks and trail mix in my park bag.
4. I know this can't really be 'carried' but use MyDisneyExperience! It is a LIFESAVER. It shows all the wait times, if there are reservations available for restaurants, character meet and greets, park hours and so much more! Definitely utilize that app while at the parks!
I hope you have an awesome trip! If you have any questions feel free to ask!
