Hi Colleen,
Thank you for sending your question to the Disney Parks Moms Panel. It sounds like you are going to have a fantastic visit at
Walt Disney World Resort, travelling with a large party is so much fun!
Being from Canada, I completely relate to your question, data packages can add up, especially for ten people. Most places at Walt Disney World Resort do have complimentary Wi-Fi, although I have found that on days with larger crowds the Wi-Fi in the Theme Parks can be slower. We visit Walt Disney World Resort several times a year and have always been fine with the complimentary Wi-Fi. My family and I do not typically purchase a data plan for our phones. The only time Wi-Fi isn't available is on Disney Transportation, the buses, monorail and boats.
I would suggest that once you have crossed the border, switch your phone to airplane mode for the duration of your visit. We had a not so pleasant phone bill after one trip where my daughter was sending pictures and messages to her grandparents throughout the vacation, without realizing that she was no longer in airplane mode and not using the Wi-Fi! It was an expensive lesson for her to learn!
I hope you have a magical time at Walt Disney World Resort, Colleen. Please let me know if you need any more assistance, we are always happy to help!
Stephanie