We just got back from a Princess Cruise to Alaska. Princess has an arrangement with Verison but not with AT&T. I was pleasantly surprised about the level of service we got with AT&T. We got service at every port, in Denali Park and sometimes even at sea. My friends had Verison and the arrangement with Princess was not cheap and they had lots of no service areas while in port. This was one of the first times on a ship that I did not get internet service. I did not need it.
I am not hear to sell AT&T but I wish I would have know this before the cruise.
Update on phone charges. We were pretty careful to have the data part of the phone service turned off while in Canada or at sea. But I guess not careful enough. I just got my phone bill and it looks like we got caught in Vancouver for Canada roaming and at see for Princess roaming. I only had about $2 on my phone but my wife had $44 in data charges. So you have to be very careful with your phone getting in and out of range of the AT&T service areas.
I have tmobile, used texting and no changes. My daughter called but I texted her back, no charges. But thanks for the info. I have unlimited data so hopefully I won't have any problems when I go on my New Year cruise. You can see if ATT will remove the changes.