May I suggest instead of treats you get them Disney pins. You can get them at the Disney store or buy them on eBay.
Pin trading at the parks is so much fun. The cast members (CMs) wear lanyards with pins on them. You approach the CM and ask to see their pins, if they have one that you like you can trade it for any Disney pin that you have.
Some CMs wear green lanyards, those will only trade with kids under 12 years old. All the others will trade with anyone.
I'm having some treats sent to Nova Scotia to help let our girls know we're going on our first Disney Trip. I'm looking for suggestions for snacks, candy or trinkets that I can have shipped to us. What's your favorite that will travel well?