We used these:
I ordered them from Land's end and had them shipped to our resort. They were less than $10 each (sale) The first day we just had a regular LE backpack that we had used for carry on luggage and it was heavy and uncomfortable. These little string bags were awesome because they have a zippered front pocket and two stretchy side mesh pockets for water bottles, etc. I found it was easier to wear it on the front instead of on my back, so I didn't always have to take it off if I wanted to get anything. I stored my camera/phone right in the front zipper pocket for easy access.
These string bags pack down into a tiny little bag so I often threw another string bag into the bottom of the first one, just in case we ended up carrying more stuff and needing an extra bag, or when we packed one with lunch stuff we just packed down the bag when we were done.
For 6 people in the middle of August when it was hotter than I could even imagine - we managed quite easily with two of those bags. It poured rain for awhile in the middle of most of the days so we bought the flimsy $1 ponchos and I had a travel umbrella in there. Then we each had one of these Contigo bottles from Costco:
They are amazing and will keep liquid cold all day! I would put ice in it and then refill it with water in the parks when needed. Sometimes we had a few plastic water bottles and it didn't matter if they got warm because we'd pour the water over the ice in these bottles and it would get cold quickly.
I did usually kept the following items in the bags:
- autograph book and pencil/pen - I shoved them in a bubble mailer envelope so they didn't get lost or damaged
- pill bottles full of quarters and pennies for the penny press machines and the shooting gallery
- small travel size kleenex, wet wipes
- our pin lanyards, and each kid had their own Disney gift card in the card holder part. If they wanted to buy something I didn't have to mess with money
- small stick of sunscreen - we sprayed sunscreen thoroughly before leaving each day
- baggie of glow bracelets, sticks, flashers etc for night events
- pill bottle with Advil, Imodium, Tums, Reactine and Dramamine
- wallet-sized first aid kit - it just had moleskin pre-cut into squares, band-Aids and alcohol wipes
That was about it! The bag was somewhat heavy at the beginning of the day because we'd shove 2-3 extra water bottles in there, but those were gone quickly. On the days we brought a lunch, I also packed one of these insulated bags into a cinch sack and it kept the sandwiches etc. cool until we ate.
I found that the key to keeping it organized is to have big and small Ziploc bags to shove stuff into. When 6 people wear ponchos, and then want to pack them back in the pack you need a place to keep them from getting everything else damp - so they went into a large ziploc and I squeezed the air out and it was dry and compact. I kept all of the lanyards and pins etc. in a ziploc when the kids weren't wearing them so that the backs didn't get lost.
It took a few days for me to realize that I really did not need my purse/wallet at Disney. Everything went on Disney cards or magic bands and I carried a few bills in a tiny change purse, just in case. It lightened my load considerably once I quit trying to shove my wallet in my backpack!
Most of all, the bags weren't too heavy or bulky and no problem to bring on the rides. The small size kept us from bringing stuff we didn't really need. When I went through bag check and saw what other people were bringing and I could not imagine carrying some of those huge bags all day!! If I needed to pack a bigger backpack I swear I'd just get one with wheels. I saw a few people with those and it seemed like such a smart idea. I would not mind hauling a bigger bag around all day as long as it wasn't aways on my shoulders.
The other thing I recommend is a lanyard-style case for your phone. I was always rummaging for mine or tucking it away in the bag for wet rides and rollercoasters. If it just hung around my neck that would have been great!
Hope that helps! I felt like we had everything we needed and as one of the designated bag-carriers, I didn't even mind carrying it.