I will skip the T's Medicare Advantage plan, stay on traditional Medicare, $8 dr-g plan, and a Plan G supplement. Yes, it will cost more up front per month, but I can go anywhere in the country for a doctor, zero copays. I cannot see a world where ATT will not slowly raise the Advantage rates or deductibles or both to the point other plans are superior, and eventually pull the plan. Besides, they want extra for Dental/Vision/Eye where so many other Advantage plans include it.
For what its worth, I also anticipated ATT messing with the pension and took lump sum well before it was privatized, and dumped all the stock years ago. Getting out from under ATT's thumb is the way to go.