One of the nice guest service features at Disneyland is the Package Express service. This will allow you to make purchases, & not have to carry them roughly with you all day! Can you imagine trying to hold all of your packages, your kids, and ride the rides?
Instead, have your purchases sent to the Newsstand, which is located near the exit. This Package Express buy allows you to pick your packages up as you are leaving the park. If you stay till closing, note that the pickup line will be very long. You should plan to leave at least an hour earlier than you had originally planned if you have packages to pick up.
You can also have your purchases sent directly to your hotel if you are staying at one of the Resort Hotels. This offers even more convenience, because you won't have to leave the park earlier, or stand in the package pickup line.
Another option is to rent a locker, and put all of your purchases in it until you are ready to leave. However, this means that you will have to walk back to the locker after each of your Disneyland purchases.