Hello, Erin! The size and type of bag that you bring with you really depends on the items that you feel you might need while you are visiting the Parks. I've been able to get by with a small purse or backpack with my 5-year old daughter, but I did use a larger bag when she was younger.
Most of the rides should be able to accommodate your backpack or a zippered tote bag. In fact, some rides even have compartments that you may be able to fit your bag into. On my most recent visit, I managed to stuff a large bag (with a small purse inside of that!) inside the compartment or between my legs on even the most thrilling rides, like Big Thunder Mountain Railroad, Seven Dwarfs Mine Train, Splash Mountain, and Space Mountain.
Alternatively, you might be interested in
renting a locker to stow your items while you and the children explore the Parks. Whatever size bag that you choose, just remember to pack a travel-sized bottle of sunscreen. I hope that you have a wonderful visit to Walt Disney World, Erin! If you have any additional questions, please do not hesitate to contact us here at the Moms Panel. Happy planning!